Initial support for in-display fingerprint sensors

* Initially based upon phh's Mi9 implementation,
  however a lot of changes have been made since.
* All device specific stuff has been moved to
  IFingerprintInscreen HIDL interface and most
  of code has been improved and refactored.

Change-Id: I52beaf6492b9daa012b5d42b858d552d1e378a2c