Add image request priority debug overlay (#56970)

Summary:
Pull Request resolved: https://github.com/facebook/react-native/pull/56970

changelog: [internal]

Add an opt-in `RCT_IMAGE_REQUEST_PRIORITY_DEBUG_OVERLAY` label for Fabric image component views so local debugging can show whether an image request is using immediate priority or the offscreen prefetch path.

Reviewed By: christophpurrer

Differential Revision: D106363533

fbshipit-source-id: ae68c9a5849dc6507f7611e02c217b674f899bd6