[ios][precompile] refactor header files generator for prebuilt React framework

[chrfalch]

Summary:

Replace the regex-based approach for parsing podspec files with a declarative configuration system for header file collection:

Add headers-config.js with explicit podspec configurations defining header patterns, directories, and subspecs

• Add vfs.js to generate VFS overlay YAML files for Clang virtual file system support
• Refactor headers.js to use the new configuration-based approach with support for nested subspecs and path preservation
• Update xcframework.js to handle the new header mapping structure with source/target paths
• This provides more reliable and maintainable header file collection for XCFramework builds by avoiding fragile regex parsing of Ruby podspec files.

Prev PR: https://github.com/facebook/react-native/pull/54840 Next PR: https://github.com/facebook/react-native/pull/54842

Changelog:

[IOS] [FIXED] - refactored header files generator for prebuilt React framework

Test Plan:

Run RNTester with prebuilt

[github-actions[bot]]

Job Summary for Gradle

Test All :: run_fantom_tests

Gradle Root Project	Requested Tasks	Gradle Version	Build Outcome	Build Scan®
react-native-github	:private:react-native-fantom:buildFantomTester	9.0.0	:x:

[github-actions[bot]]

Job Summary for Gradle

Test All :: run_fantom_tests

Gradle Root Project	Requested Tasks	Gradle Version	Build Outcome	Build Scan®
react-native-github	:private:react-native-fantom:buildFantomTester	9.0.0	:x: