Implement supplemental description API

Design doc: https://docs.google.com/document/d/11IQj50EhE_UIIRmlpO32e5pA7v5DWBxnOF4JI6UOPTI/edit?usp=sharing

Test: CTS test added
Flag: android.view.accessibility.supplemental_description
Bug: 375266174

Change-Id: Ieba7d81ec7c833cdd39a97e3c4b35d2117b739e6
8 files changed