docs: Add Kotlin & Swift FP plugins examples (#1902)

* chore(docs): add Kotlin FP example

* chore(docs): add Swift FP plugin

package/example/ios/vc_example_cocoapod_utils.rb

@@ -0,0 +1,63 @@
+# Let's use ReactNativePodsUtils utility class to make it more maintainable
+require Pod::Executable.execute_command('node', ['-p',
+  'require.resolve(
+    "react-native/scripts/cocoapods/utils.rb",
+    {paths: [process.argv[1]]},
+  )', __dir__]).strip
+
+#
+# In order to compile the project with disabled frame processors mode
+# the codebase of example swift frame processor plugin needs to be put
+# behind the swift compiler flag
+# 
+# Let's set the flag based on the same logic like in library's podspec file
+# 
+def set_frame_processor_swift_flag_in_example_project(installer)
+  has_worklets = does_example_have_worklets_enabled(installer)
+  set_swift_compiler_flag_in_project(installer, has_worklets)
+end
+
+def does_example_have_worklets_enabled(installer)
+  forceDisableFrameProcessors = false
+  if defined?($VCDisableFrameProcessors)
+    forceDisableFrameProcessors = true
+  end
+  has_worklets = ReactNativePodsUtils.has_pod(installer, "react-native-worklets-core") && !forceDisableFrameProcessors
+end
+
+# 
+# It's similar to:
+# - [`ReactNativePodsUtils.add_compiler_flag_to_project`](https://github.com/facebook/react-native/blob/ad5213718377017ec6d2a057541f6d4c57e0507d/packages/react-native/scripts/cocoapods/utils.rb#L384)
+# - [`ReactNativePodsUtils.remove_compiler_flag_from_project`](https://github.com/facebook/react-native/blob/ad5213718377017ec6d2a057541f6d4c57e0507d/packages/react-native/scripts/cocoapods/utils.rb#L395)
+# but uses utils for setting "OTHER_SWIFT_FLAGS" compiler flag, which is unsupported by ReactNativePodsUtils
+# 
+def set_swift_compiler_flag_in_project(installer, has_worklets)
+  projects = ReactNativePodsUtils.extract_projects(installer)
+  projects.each do |project|
+    project.build_configurations.each do |config|
+      flag = "-DVISION_CAMERA_ENABLE_FRAME_PROCESSORS"
+      if has_worklets
+        set_swift_flag_in_config(config, flag)
+      else
+        remove_swift_flag_in_config(config, flag)
+      end
+    end
+    project.save()
+  end
+end
+
+# 
+# It's similar to [`ReactNativePodsUtils.set_flag_in_config`](https://github.com/facebook/react-native/blob/ad5213718377017ec6d2a057541f6d4c57e0507d/packages/react-native/scripts/cocoapods/utils.rb#L414),
+# but supports "OTHER_SWIFT_FLAGS" compiler flag
+# 
+def set_swift_flag_in_config(config, flag)
+  ReactNativePodsUtils.add_flag_for_key(config, flag, "OTHER_SWIFT_FLAGS")
+end
+
+# 
+# It's similar to [`ReactNativePodsUtils.remove_flag_in_config`](https://github.com/facebook/react-native/blob/ad5213718377017ec6d2a057541f6d4c57e0507d/packages/react-native/scripts/cocoapods/utils.rb#L421),
+# but supports "OTHER_SWIFT_FLAGS" compiler flag
+# 
+def remove_swift_flag_in_config(config, flag)
+  ReactNativePodsUtils.remove_flag_for_key(config, flag, "OTHER_SWIFT_FLAGS")
+end