Use RootTDAOrganizer to determine caption visibility

This is a remnant of ag/26927955.

It's possible that root TDA info is unavailable when we need to decide
the visibility of decor captions if a display and a task on that display
show up roughly at the same time. Instead of ensuring the order of
events, it's easier to "guess" the need of captions using other signals.
Ultimately other modes of freeform tasks (e.g. desktop mode) need to
have their own implementations of window decors & window decor view
models, in which they have full knowledge of whether their window decors
should show up without relying on info from higher containers. Root
TDA's windowing mode should also be controlled by WM shell in those
cases as well.

Bug: 333724879
Test: Captions show up as expected.
Change-Id: Ia3f0ffb3ee02fb9a993952dc3cfa7ac210b2f160