Allow system windows for virtual devices only on trusted displays.

Today CREATE_VIRTUAL_DEVICE permission is equivalent to
ADD_TRUSTED_DISPLAY permission - they're always granted together.
However, we want to decouple these in the future and allow for
"limited" virtual devices that cannot create trusted displays.

Bug: 350007866
Fix: 370656717
Test: cts
Flag: android.companion.virtualdevice.flags.status_bar_and_insets
Change-Id: I6cf021f292d6bf1ea4d4da4722c98b2d1a547c73