Add CCACHE_BINARY path to Xcode build settings and use it in ccache scripts (#48257)

Summary:
When building a react native app from Xcode and ccache has been set to be used, the `ccache-clang.sh` and `ccache-clang++.sh` scripts cannot find `ccache`, because Xcode PATH does not include ccache binary.
What I've done is setting a `CCACHE_BINARY` user-defined Xcode setting containing the result of executing `command -v ccache` during pod install execution and directly calling it in ccache scripts, set by ReactNativePodsUtils when ccache is enabled.

Fixes https://github.com/facebook/react-native/issues/46126

## Changelog:

[IOS] [FIXED] - fix ccache not found error exporting ccache binary path as Xcode user-defined setting to be used by ccache scripts

Pull Request resolved: https://github.com/facebook/react-native/pull/48257

Test Plan: Correctly builds helloworld and RNTester apps using ccache by enabling it at pod install time: `USE_CCACHE=1 pod install`.

Reviewed By: christophpurrer

Differential Revision: D67280700

Pulled By: cipolleschi

fbshipit-source-id: 5478a191f9bd77606a56ccd340fea225ab62d4bc