Enhanced Connectivity Dev Toggle

Add Enhanced Connectivity Developer option switch. This switch will
allow the connectivity thermal power manager to actively shutoff 5G in
order to save power when cellular throughput is below the set threshold.

ScreenShots: https://drive.google.com/drive/folders/109VTTXqIn5Teg6daHpNHV7z13MmEEb7Q?usp=sharing

Bug: 147305171
Test: make RunSettingsRoboTests ROBOTEST_FILTER=EnhancedConnectivityPreferenceControllerTest
Test: On-device using developer option menu

Change-Id: I311cfcadb8325db30ff4917959414b5a7d108bcc