Fancy animated button cannot be stopped by keyboard alone

[rzhao271]

Testing #328440

Verify keyboard behavior: Tab reaches links, the picker when present, and close; Enter/Space activate controls; Escape dismisses.

1. Start dictation
2. Tab to the fancy microphone button or its toolbar element surrounding it (there seem to be two separate focus options for that button)
3. Try pressing space or enter
4. 🐛 Nothing happens

[meganrogge]

The idea here is to use the keybindings to start and stop, but yes, we should also make enter or space work too.