Simplify some legacy path of resume activity

- Simplify the "notUpdated" logic in resumeTopActivity. Because
  configuration change should only either relaunch or dispatch
  change to activity, the purpose of early return is only to
  avoid scheduling. The diff-top condition never satisfies.
- Pass DisplayContent directly to ensureVisibilityAndConfig
  since ATM/WM hierarchy is unified.
- Simplify usages if completeResumeLocked. It doesn't contain
  any IPC so it should never throw exception. And the visibility
  should be set by the callers (resumeTopActivity/realStartActivity)
  rather than itself. That reduces redundant visibility changes
  when launching acitivity while device is locked.

Bug: 163976519
Test: RootWindowContainerTests

Change-Id: I90d68e90ea89bb87171f8f52e74b8b51fae057c8