feat: Add pixelFormat field (#559)

* Add `mediaSubType` field to device formats

* Create FourCharCode `toString` extension

* Move pixelFormat -> `AVCaptureDevice.Format+toDictionary`

* `mediaSubType` -> `pixelFormat` + non-optional

* ts pixelFormat `string` -> specific formats

* Add default pixelFormat value of `420v` on Android

Co-authored-by: tcoldwell72 <31568400+tcoldwell72@users.noreply.github.com>

ios/Extensions/AVCaptureDevice.Format+toDictionary.swift

@@ -42,12 +42,13 @@ extension AVCaptureDevice.Format {
           "maxFrameRate": $0.maxFrameRate,
         ]
       },
+      "pixelFormat": CMFormatDescriptionGetMediaSubType(formatDescription).toString()
     ]
 
     if #available(iOS 13.0, *) {
       dict["isHighestPhotoQualitySupported"] = self.isHighestPhotoQualitySupported
     }
-
+    
     return dict
   }
 }

ios/Extensions/FourCharCode+toString.swift

@@ -0,0 +1,17 @@
+//
+//  FourCharCode+toString.swift
+//  VisionCamera
+//
+//  Created by Thomas Coldwell on 28/10/2021.
+//  Based off this SO answer: https://stackoverflow.com/a/25625744
+//
+
+extension FourCharCode {
+    func toString() -> String {
+        var s: String = String (UnicodeScalar((self >> 24) & 255)!)
+        s.append(String(UnicodeScalar((self >> 16) & 255)!))
+        s.append(String(UnicodeScalar((self >> 8) & 255)!))
+        s.append(String(UnicodeScalar(self & 255)!))
+        return (s)
+    }
+}