Request fine location permission for Bluetooth discovery
This branch requests the fine location permission rather than the coarse location permission for Bluetooth discovery. This will be needed when we raise our target API version to 29.
Existing users on Android 6+ will be prompted again for the location permission the next time they add a contact in person. Existing users on older Android versions will be informed about the new permission by the package installer.
Closes #1721 (closed)