Initiate uninstall on confirmation from the user

Once the user grants permission to uninstall, get an uninstall id, register a broadcast receiver and kick off the uninstall.

Bug: 182205982
Test: builds successfully
Test: No CTS Tests. Flag to use new app is turned off by default

Change-Id: I81177783df4f2b9357b2fd90cc8284f02befd204