Refactored how we create umbrella, modulemap and header files (#52286)

Summary:
To make sure we are exposing the same public API to swift as without prebuilt, this commit changes the follow:

- ModuleMap / Umbrella file is generated from template, not dynamically to align with non-prebuilt (cocoapods). This is temporary, we are already working toward a solution to generate them dynamically.
- Headers are extracted by reading from podspec files and expanding their globs. This is now easy since we can use the podspec_sources function to look for file globs.

## Changelog:
[Internal] -  refactored header/umbrella/modulemap generation for prebuild

Pull Request resolved: https://github.com/facebook/react-native/pull/52286

Test Plan:
- Run RN-tester with/without prebuilts
- Create new RN app based on nightly, build with/without prebuiltsTo make sure we expose all the swift features that we should, we expose and declare a variable from React_RCTAppDelegate

Rollback Plan:

Reviewed By: cortinico

Differential Revision: D77368255

Pulled By: cipolleschi

fbshipit-source-id: 88e2c9d1622753895c8667a9b5aeae4a0d332cc4