Complete the acquireHardware API implementation in the TvInputHardwareManager

This CL:
1. Finish the logic in TIHM to utilize the TRM for a client priority check.
2. FInish the TRM isHigherPriority API to allow the TIHM to compare the
client priority.
3. Finish the TRM isForeground method to check if a process is
foreground or not.
3. Add unit test for TRM isHigherPriority.

Test: atest com.android.server.tv.tunerresourcemanager
Bug: 155339425
Change-Id: I3887ccad31195d3386f1fc6b3de3e641df91092f