Fix onSubmitEditing firing twice for hardware Enter in multiline TextInput on Android

[lazerg]

Summary:

Fixes #58990.

When a hardware Enter key is pressed in a multiline TextInput with submitBehavior="submit", TextView calls the editor action listener on key down, and because the listener returns true it sets enterDown and calls the listener again on key up with the same IME_NULL action. Our listener doesn't look at the key event, so it dispatches onSubmitEditing both times. Single-line inputs don't hit this because ReactEditText.onKeyUp already consumes Enter before TextView sees it, and IME action buttons pass a null event.

The listener now ignores the key-up call and just keeps consuming it. TextView only calls the listener on key up after the key down was already handled, so nothing else changes.

Changelog:

[ANDROID] [FIXED] - Fix onSubmitEditing firing twice when pressing a hardware Enter key in a multiline TextInput with submitBehavior="submit"

Test Plan:

Added ReactTextInputSubmitEditingTest, which sends an Enter key down and key up to a multiline TextInput with submitBehavior="submit" and checks that only one submit event is dispatched. It fails on main (2 dispatches) and passes with this change.

./gradlew :packages:react-native:ReactAndroid:testDebugUnitTest --tests "com.facebook.react.views.textinput.*"

ReactTextInputPropertyTest (28) and the new test pass.