Implement method for get previously connected devices

According new feature requirement, this cl will implement following items:

- Show the previously connected devices in the list
- Show the sub title of MediaDevice
- Connect the Bluetooth device when user click the disconnect Bluetooth device.
- Add new rule Phone device always in the top and "Connected Devices" should
  appear above "Previously Connected Devices" in the list in naive rule.

Bug: 127201385
Test: make -j50 RunSettingsLibRoboTests
Change-Id: I19d5f69d394eb0359d42979057ef41f62b6545db