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
Due to the difference in nature, the iOS and Android implementations are
completely different:
iOS: MPVolumeView is used, which allows us to place a button which will launch a
native route picker provided by iOS itself. This view is different depending on
the iOS version, with the iOS 11 version being more complete.
Android: A completely custom component is used, which displays a bottom sheet
with the device categories, not devices individually. This is akin to the sheet
in the builtin dialer.