Remove `REACT_NATIVE_MINOR_VERSION` build flag (#4422)

## Description

This PR removes the `REACT_NATIVE_MINOR_VERSION` build flag and fixes
the `target_compile_reactnative_options` call in the Android
`CMakeLists`.

The only consumer of `REACT_NATIVE_MINOR_VERSION` was a >= 81 check in
`RNGHRuntimeDecorator.cpp`, which is always true on supported
react-native versions. If a version check becomes necessary in the
future, react-native ships `<cxxreact/ReactNativeVersion.h>` with the
`REACT_NATIVE_VERSION_MINOR` macro, available on all platforms and build
systems.

The `target_compile_reactnative_options` block added in #3688 never
executed: it ran before `find_package(ReactAndroid)` defines
`ReactAndroid_VERSION_MINOR`, referenced an undefined `LIB_TARGET_NAME`,
and was missing the include of `react-native-flags.cmake` that defines
the function. This PR fixes it to match how reanimated and worklets use
it. Note that this applies RN_SERIALIZABLE_STATE and HERMES_V1_ENABLED=1
to our JNI target for the first time, matching how ReactAndroid itself
is built.

## Test plan

- basic-example builds and launches on iOS (pod install + yarn ios)
- basic-example builds on Android (assembleDebug, -Wall -Werror, no new
warnings)
- compile_commands.json confirms RN_SERIALIZABLE_STATE and
HERMES_V1_ENABLED=1 are applied to all translation units
- basic-example builds under the experimental SwiftPM setup from
react-native 0.87
- pod ipc spec evaluates the modified podspec cleanly