[ios][prebuild] build xcframeworks from prebuild script

[chrfalch]

Summary

This commit adds support for building XCFrameworks from the prebuild-script

• Added build script to help build xcframeworks
• Added full header file structure
• Added calling the build script from the main prebuild script

TODO: We need to add resources / privacy bundles

Changelog:

[IOS] [ADDED] - Added building XCFframework from the prebuild script

Test Plan:

Run prebuild script and verify that XCFrameworks are successfully built.