This PR removes the old `ToggleButton` component, replacing it with the
newer `ToggleButtonGroup` component in the couple of places that used to
use it. Ended up also adding a few more methods to the newer toggle
button group so the UI for the extensions page and the debugger main
picker didn't get visually impacted much. Then, as I was already in the
extensions page, decided to bake in some reasonably small UI
improvements to it as well.
Release Notes:
- N/A
ba596267d8