Push active dream component to WindowManager instead of pulling.

Instead of pulling the active dream component, we push the component
when a dream is started. This ensures that the active component remains
in sync with the currently active dream.

Bug: 246091760
Test: flashed device and verified dreams are working correctly
Change-Id: Ifece2dc62486b74794f0d333d19bec2ab3bc9229
5 files changed