Even more screen reader/accessibility improvements
This is more a focus on the initial setup flow:
- Announce the "Compatible with Mastodon" button properly
- Fix tabbing between the list view and the search field on the servers page
- Allow tabbing to the "Custom Server" list item
- Allow tabbing through the rules, thus being able to read them individually with a screen reader.
- Read out the post author and interaction labels, instead of it just saying "[display name] button"
- Add missing text for numerous tool buttons in the status composer