Grey the previously connected device preference

* Add PreviouslyConnectedDevicePreferenceController to handle the preference should be
  enable or disable.
  Example: If there are no previously connected devices disable the preference otherwise
  enable it.
* Add PreviouslyConnectedDevicePreferenceControllerTest
  1. Verify the callback can be registered and unregistered
  2. Verify the preference is enable when there
     have more than 1 previously connected device
  3. Verify the preference is disable when there
     have no previously connected device

Bug: 78250052
Test: make -j50 RunSettingsRoboTests
Change-Id: I31b5d416aaf907c3bbf1cb61de6e7401463e3df7
Merged-In: I31b5d416aaf907c3bbf1cb61de6e7401463e3df7