Fix wake lock logic during Dream startup

Fixes a crash that would happen in all dreams
that did not have permission to acquire wake locks.
Instead moves the wake lock logic into the system
process. Also fixes a bug in DozeService where the
wake lock was not held until dozing was actually
properly initialized.

Fixes: 31612287
Bug: 31044352
Related-CL: I85955a2b7d6bad5171accbc336117a9660b1b198
Test: adb shell settings put secure screensaver_components com.android.dreams.basic/.Colors; adb shell service call dreams 1

Change-Id: Idb3f921ee71b6da6c2ab0c44c332ef91f93ddbc0