Several fixes to GH bottom area on mobile.

1. Always show the "go to dream" button if charging.
2. Position the "go to dream" button in the bottom right corner.
3. Tapping the "go to dream" button when dreams are disabled
   goes to settings.
4. Lock icon is always at the bottom of the screen, even on
   devices with UDFPS.

Bug: 382693988
Bug: 382739998
Test: atest CommunalSettingsRepositoryImplTest
Test: atest CommunalToDreamButtonViewModelTest
Flag: com.android.systemui.glanceable_hub_v2
Change-Id: Id7413b41c4d4d52780431fde2b1878fe8c1fd02b