add IInstalld.controlDexOptBlocking call

- This allows cancelling pending dexoptimization by killng the currently
  running dex2oat process and block future dexopt calls.
- As the only client is system server and installd restarts, it relies on
  the client to restore the state to unblcoked state properly.

Bug: 179094324
Bug: 156537504

Test: Run added test with existing tests
      atest installd_dexopt_test installd_service_test

Change-Id: I73bff6e4cd4473b57d0f06b062dd035dbda6b496