feat: Sync Frame Processors (plus runAsync and runAtTargetFps) (#1472)

Before, Frame Processors ran on a separate Thread.

After, Frame Processors run fully synchronous and always at the same FPS as the Camera.

Two new functions have been introduced:

* `runAtTargetFps(fps: number, func: () => void)`: Runs the given code as often as the given `fps`, effectively throttling it's calls.
* `runAsync(frame: Frame, func: () => void)`: Runs the given function on a separate Thread for Frame Processing. A strong reference to the Frame is held as long as the function takes to execute.

You can use `runAtTargetFps` to throttle calls to a specific API (e.g. if your Camera is running at 60 FPS, but you only want to run face detection at ~25 FPS, use `runAtTargetFps(25, ...)`.)

You can use `runAsync` to run a heavy algorithm asynchronous, so that the Camera is not blocked while your algorithm runs. This is useful if your main sync processor draws something, and your async processor is doing some image analysis on the side. 

You can also combine both functions.

Examples:

```js
const frameProcessor = useFrameProcessor((frame) => {
  'worklet'
  console.log("I'm running at 60 FPS!")
}, [])
```

```js
const frameProcessor = useFrameProcessor((frame) => {
  'worklet'
  console.log("I'm running at 60 FPS!")

  runAtTargetFps(10, () => {
    'worklet'
    console.log("I'm running at 10 FPS!")
  })
}, [])
```



```js
const frameProcessor = useFrameProcessor((frame) => {
  'worklet'
  console.log("I'm running at 60 FPS!")

  runAsync(frame, () => {
    'worklet'
    console.log("I'm running on another Thread, I can block for longer!")
  })
}, [])
```

```js
const frameProcessor = useFrameProcessor((frame) => {
  'worklet'
  console.log("I'm running at 60 FPS!")

  runAtTargetFps(10, () => {
    'worklet'
    runAsync(frame, () => {
      'worklet'
      console.log("I'm running on another Thread at 10 FPS, I can block for longer!")
    })
  })
}, [])
```

ios/Frame Processor/FrameProcessorRuntimeManager.mm

@@ -22,6 +22,7 @@
 #import "JsiWorkletContext.h"
 #import "JsiWorkletApi.h"
 #import "JsiWorklet.h"
+#import "JsiHostObject.h"
 
 #import "FrameProcessorUtils.h"
 #import "FrameProcessorCallback.h"
@@ -30,7 +31,7 @@
 // Forward declarations for the Swift classes
 __attribute__((objc_runtime_name("_TtC12VisionCamera12CameraQueues")))
 @interface CameraQueues : NSObject
-@property (nonatomic, class, readonly, strong) dispatch_queue_t _Nonnull frameProcessorQueue;
+@property (nonatomic, class, readonly, strong) dispatch_queue_t _Nonnull videoQueue;
 @end
 __attribute__((objc_runtime_name("_TtC12VisionCamera10CameraView")))
 @interface CameraView : UIView
@@ -38,6 +39,7 @@ __attribute__((objc_runtime_name("_TtC12VisionCamera10CameraView")))
 @end
 
 @implementation FrameProcessorRuntimeManager {
+  // Running Frame Processors on camera's video thread (synchronously)
   std::shared_ptr<RNWorklet::JsiWorkletContext> workletContext;
 }
 
@@ -59,16 +61,15 @@ __attribute__((objc_runtime_name("_TtC12VisionCamera10CameraView")))
   };
   auto runOnWorklet = [](std::function<void()>&& f) {
     // Run on Frame Processor Worklet Runtime
-    dispatch_async(CameraQueues.frameProcessorQueue, [f = std::move(f)](){
+    dispatch_async(CameraQueues.videoQueue, [f = std::move(f)](){
       f();
     });
   };
 
-  workletContext = std::make_shared<RNWorklet::JsiWorkletContext>("VisionCamera");
-  workletContext->initialize("VisionCamera",
-                             &runtime,
-                             runOnJS,
-                             runOnWorklet);
+  workletContext = std::make_shared<RNWorklet::JsiWorkletContext>("VisionCamera",
+                                                                  &runtime,
+                                                                  runOnJS,
+                                                                  runOnWorklet);
 
   NSLog(@"FrameProcessorBindings: Worklet Context Created!");
 
@@ -136,28 +137,17 @@ __attribute__((objc_runtime_name("_TtC12VisionCamera10CameraView")))
   NSLog(@"FrameProcessorBindings: Installing global functions...");
 
   // setFrameProcessor(viewTag: number, frameProcessor: (frame: Frame) => void)
-  auto setFrameProcessor = [self](jsi::Runtime& runtime,
-                                  const jsi::Value& thisValue,
-                                  const jsi::Value* arguments,
-                                  size_t count) -> jsi::Value {
+  auto setFrameProcessor = JSI_HOST_FUNCTION_LAMBDA {
     NSLog(@"FrameProcessorBindings: Setting new frame processor...");
-    if (!arguments[0].isNumber()) throw jsi::JSError(runtime, "Camera::setFrameProcessor: First argument ('viewTag') must be a number!");
-    if (!arguments[1].isObject()) throw jsi::JSError(runtime, "Camera::setFrameProcessor: Second argument ('frameProcessor') must be a function!");
-
     auto viewTag = arguments[0].asNumber();
-    NSLog(@"FrameProcessorBindings: Converting JSI Function to Worklet...");
     auto worklet = std::make_shared<RNWorklet::JsiWorklet>(runtime, arguments[1]);
 
-    RCTExecuteOnMainQueue([=]() {
+    RCTExecuteOnMainQueue(^{
       auto currentBridge = [RCTBridge currentBridge];
       auto anonymousView = [currentBridge.uiManager viewForReactTag:[NSNumber numberWithDouble:viewTag]];
       auto view = static_cast<CameraView*>(anonymousView);
-
-      NSLog(@"FrameProcessorBindings: Converting worklet to Objective-C callback...");
-
-      view.frameProcessorCallback = convertWorkletToFrameProcessorCallback(workletContext->getWorkletRuntime(), worklet);
-
-      NSLog(@"FrameProcessorBindings: Frame processor set!");
+      auto callback = convertWorkletToFrameProcessorCallback(self->workletContext->getWorkletRuntime(), worklet);
+      view.frameProcessorCallback = callback;
     });
 
     return jsi::Value::undefined();
@@ -168,12 +158,8 @@ __attribute__((objc_runtime_name("_TtC12VisionCamera10CameraView")))
                                                                                                          setFrameProcessor));
 
   // unsetFrameProcessor(viewTag: number)
-  auto unsetFrameProcessor = [](jsi::Runtime& runtime,
-                                const jsi::Value& thisValue,
-                                const jsi::Value* arguments,
-                                size_t count) -> jsi::Value {
+  auto unsetFrameProcessor = JSI_HOST_FUNCTION_LAMBDA {
     NSLog(@"FrameProcessorBindings: Removing frame processor...");
-    if (!arguments[0].isNumber()) throw jsi::JSError(runtime, "Camera::unsetFrameProcessor: First argument ('viewTag') must be a number!");
     auto viewTag = arguments[0].asNumber();
 
     RCTExecuteOnMainQueue(^{
@@ -185,7 +171,6 @@ __attribute__((objc_runtime_name("_TtC12VisionCamera10CameraView")))
 
       auto view = static_cast<CameraView*>(anonymousView);
       view.frameProcessorCallback = nil;
-      NSLog(@"FrameProcessorBindings: Frame processor removed!");
     });
 
     return jsi::Value::undefined();