Improve LockStateTrackingRule

- Make assertLocked and assertUnlocked check
  KeyguardManager#isDeviceLocked, in addition to what they were checking
  before.  This is important, as this verifies what TrustManagerService
  (and thus also Keystore) considers the device locked state to be.

- Rename assertUnlocked to assertUnlockedAndTrusted.  This makes it
  clear that it checks for trusted (which implies unlocked), not just
  unlocked (which does not necessarily imply trusted).

- Rename the inner class LockState to TrustState.  This makes it clear
  what it actually is.

- Improve the class comment.

Bug: 296464083
Bug: 298249081
Flag: TEST_ONLY
Test: atest TrustTests
Change-Id: I865ec19dff7ebe00ff083da29154e3c9cb846574