All apps icons should become clickable

b/29761088
b/29610290

> Workspace transition state was not being properly set which
caused onClick to not allow apps to launch. Temporary solution:
do not call the onLauncherTransitionPrepare inside
AllAppsTransitionController.

> Fixing another important bug which doesn't properly set workspace
state to correct alpha value because hotseat background drawable
is null when home is triggered from settings app after wallpaper is
changed. The color extractor has not figured out how hotseat drawable
color should be set to immediately after wallpaper change.

Change-Id: I9f797dbda6c73c71816e5070ed4da37099b26a6d