This commit refactors device selection (more heavily on iOS) to make it
consistent across platforms.
Due to its complexity I couldn't break out each step into separate commits,
apologies to the reviewer.
Changes made to device handling:
- speaker is always the default, regardless of the mode
- "Phone" shows as a selectable option, even in video call mode
- "Phone" is not displayed when wired headphones are present
- Shared device picker between iOS and Android
- Runtime device updates while the picker is open
Saúl Ibarra Corretgé