[Sb refactor] Add `dataEnabled` tracking to mobile repos

This CL adds the `dataEnabled` property to `MobileConnectionRepository`.
`dataEnabled` maps to `TelephonyManager.isDataConnectionAllowed`, and it
is polled whenever telephony sends updates to us.

Also threaded this field down to the view model to use in our logic for
showing / hiding the network type indicator.

Test: atest MobileConnectionRepositoryTest MobileIconsInteractorTest
MobileIconViewModelTest
Bug: 240492102

Change-Id: I5b4cae651dcf50a3dd4abc4d3e803e4386320cbd