[Audiosharing] UI refinement.

1. Add top summary for Audio sharing page.
2. Move Audio sharing entrance to the second place on Connection
   preferences page.
3. Make Audio sharing page searchable.
4. Add On/Off summary to Audio sharing preference on Connection
   preference page.

Test: atest
Bug: 305620450
Change-Id: I00019e53563afc0a539934fbdfa949c3401e78b9