Change UI for wireless AP tether band selection

We decided to use the list preference after all due to
some devices not supporting various combinations of AP
configurations. This change makes it so that there are
three different UIs depending on the configurations
which are supported.
- 5.0 GHz unsupported: disable the preference and just
set the value to 2.4 GHz
- all supported, no dual mode: allow the user to choose
EITHER 2.4 GHz or 5.0 GHz
- all supported, dual mode: allow the user to choose
2.4 GHz or BOTH 2.4 GHz & 5.0 GHz with 5.0 being
preferred

Test: atest SettingsRoboTests
Bug: 80315296
Change-Id: I888d35811a98b8cf0155a3cb96c42ff762763378
Merged-In: I888d35811a98b8cf0155a3cb96c42ff762763378