[lazerg]

Summary:

With useTraitHiddenOnAndroid or enableViewCulling on, mounting a ScrollView on Android crashes with NoSuchKeyException: scrollAwayPaddingBottom. loadFabricScrollState reads scrollAwayPaddingBottom from the state data, but the C++ ScrollViewState never had that field, so getDynamic() doesn't include it and the value Kotlin writes in forceUpdateState gets dropped on the way back.

This adds scrollAwayPaddingBottom to ScrollViewState and reads/writes it in the serializable state, the same way scrollAwayPaddingTop already works.

Fixes #59654

Changelog:

[ANDROID] [FIXED] - Fix ScrollView crash with NoSuchKeyException: scrollAwayPaddingBottom when useTraitHiddenOnAndroid or enableViewCulling is on

Test Plan:

Added a ScrollViewStateTest case (under RN_SERIALIZABLE_STATE) checking that getDynamic() includes scrollAwayPaddingBottom and that it survives a round trip through the dynamic constructor. I ran it locally against the header with Homebrew folly and gtest:

clang++ -std=c++20 -DRN_SERIALIZABLE_STATE ... ScrollViewState.cpp -lgtest -lgtest_main -lfolly
[  PASSED  ] 1 test.

Without the fix it doesn't compile, since the field doesn't exist. I updated the three Frameworks C++ API snapshots by hand and checked them against python -m scripts.cxx-api.parser --validate output for ScrollViewState. I also ran the repo's clang-format on both files. I didn't run the reproducer app on a device.