feat: move test app to react-native-test-app

[Saadnajmi]

TODO:

• Test iOS Paper
• Test iOS Fabric
• Test Android Paper
• Test Android Fabric

Summary

I am interested in (eventually) adding macOS support to react-native-skia. Generally the first step to this is to first move the repository's test app to React Native Test App. This repo offers a few benefits:

1. RNTA handles the native code of an example app for you (similar to expo's continuous native generation), so you only have to worry about your apps' JS.
2. Backwards and forwards compatibility across a few Raect Native minor versions
3. (Most importantly) The ability to easily add support for new platforms. In this case, of the 3 extra platforms RNTA supports ( macOS, visionOS, windows), the ones I know how to port after this change are macOS and visionOS.

Notes

• I dropped the babel plugin transform-inline-environment-variables because things seemed to bundle fine without it?
• I dropped a few other dependencies in the test app I didn't know what they were doing. Most likely I'll add a couple back as I try to get the CI to pass.

Test Plan

I got the iOS example app to run with the old architecture so far: