[RN][iOS] Fix compiler flags passed to libraries

[cipolleschi]

Summary:

Thanks to this issue and this PR in react-native-webview, we discovered that the compiler_flags that we were passing to a library that was using install_modules_dependencies were not correct when the RCT_NEW_ARCH_ENABLED flag was set.

With this change, we make sure that, when this flag is turned on, we pass the -DRCT_NEW_ARCH_ENABLED flag to the library.

Changelog:

[iOS][Fixed] - properly pass the -DRCT_NEW_ARCH_ENABLED=1 flag to libraries that use install_modules_dependencies

Test Plan:

Tested locally by:

1. creating a new app with 0.73
2. adding react-native-webview
3. seeing that the destroyWebView method was greyed out (not compiled)
4. applying the changes
5. rebuild and see that the destroyWebView method was not greyed out anymore (compiled).
6. Running the app and verifying that the debugger was stepping into the function.

BEFORE	AFTER

[analysis-bot]

Platform	Engine	Arch	Size (bytes)	Diff
android	hermes	arm64-v8a	8,500,344	-9,385,402
android	hermes	armeabi-v7a	n/a	--
android	hermes	x86	n/a	--
android	hermes	x86_64	n/a	--
android	jsc	arm64-v8a	9,754,927	-11,485,153
android	jsc	armeabi-v7a	n/a	--
android	jsc	x86	n/a	--
android	jsc	x86_64	n/a	--

Base commit: cb307b9
Branch: main