Sharesheet/Resolver a11y adjustments

1. Announce app name with direct share targets
2. Don't speak 'heading' in direct share rows
3. Don't close resolver/sharesheet when swiping left
4. Talkback will announce # of rows and columns for sharesheet

Fixes: 141908464
Fixes: 155153657
Fixes: 151897812
Fixes: 149437892
Fixes: 80319063
Test: talkback
Change-Id: I16586208407ba56814d3cf69648e660bded72ccf