Add the explicitly mutable flag for creating a PendingIntent

- Android S+ to specify explicitly either FLAG_MUTABLE or FLAG_IMMUTABLE
  when creating a PendingIntent.
- Suggest to use the FLAG_IMMUTABLE as default. Change it to
  FLAG_MUTABLE while errors occur.

Fixes: 172207262
Fixes: 172207195
Fixes: 172205385
Fixes: 172204525
Fixes: 172205897
Test: build pass, manual test to paring blutooth device and doing
seamless transfer

Change-Id: Ic37b37bdbe6de6bdbad741985d3a920334240d80