Persist Bluetooth CoD config value across reboot

This CL creates a new Settings value for Bluetooth CoD so that it may
persist across reboots. Once the adapter is up, it sets the CoD value to
the one stored in the config.

Bug: 36015415
Test: Verified by storing a value through a test app and restarting the
machine to ensure it's picked up.

Change-Id: I00aaa35197e43af7460f478c0f9c8e0ceec55579