Makes sure ImeISP invokes onImeRequestedChanged

This makes sure that OnImeRequestedChangedListener#onImeRequestedChanged
is invoked with the latest window token and visibility when IME input
target changes with RemoteInsetsControlTarget.

In multi-window mode, notifying the IME input target change to IMMS
depends on that calling setImeInputTargetRequestedVisibility on
RemoteInsetsControlTarget eventually calls back system server the
visibility change. However, this can only happen the requested
visibility changes. It's possible that the reuqested visibiltiy is the
same but input target changes, which happens when the input target
window moves in between the connected displays.

This is a similar fix as [1] but for different call path.

[1] I96ffe688ae5eb32e325f3f7c9c62b392f7287100

Bug: 438569349
Bug: 411099169
Test: ImeInsetsSourceProviderTest
Test: Open freeform window on desktop, focus on an editor. Moving it to another display restarts input
Flag: EXEMPT bug fix
Change-Id: Ia2666bc96bb6133830a90711bce29bcccfec91e8