Writing tools: API for EditorInfo 2/n

Introduces support for writing tools in EditorInfo. by default its
enabled on all editors and app/toolkit can opt-out if needed.

Bug: 373788889
Flag: android.view.inputmethod.writing_tools
Test: atest CtsInputMethodTestCases
API-Coverage-Bug: 378735851
Change-Id: I3c1d2be02a578a8c8633418c982df1c78553b936