update dexopt to support cancellation

- Installer.dexopt now returns true (when completed) or false (when
  cancelled): reflect IInstalld change
- added Installer.controlDexOptBlocking to block or unblock dexopt
  : already added to IInstalld
- add PackageDexOptimizer.DEX_OPT_CANCELLED code with
  PackageDexOptimizer.DexOptResult annotation
- Change mInstaller's lock access:
  controlDexOptBlocking should access it without mInstallLock
  all other existing mInstaller access should be done under
    mInstallLock

Bug: 179094324
Bug: 156537504

Test: build only. Following CLs will include unit tests and manual test
      instruction.
Change-Id: I188bc04f76776e8117418ef1fd7c5311c9492758