Allow WindowOrganizerController to handle DisplayAreas

The current code for WindowOrganizerController only allows transactions
to be submitted for Tasks. This change makes the request handing more
generic so it should allow for transactions to be submitted for all
WindwoContainers. However, we're limiting the requests to Tasks and
DisplayAreas to avoid any larger issues.

There are some transactions that will only work for Tasks so there
is a separate code path to handle Task specific transactions.

Test: WindowOrganizerTests
Bug: 152116619
Bug: 152114574
Change-Id: I916a8f0c92be490318ee45e09f6a5e8a4ee6ec62