Add boundsChangeTransaction for Task pending mode change

This associates a surfaceflinger bounds change with a task's
surface provided that task will become organized by the end
of a WindowContainer transaction. Without this, there's no
way to synchronize a new frame due to bounds-change with
said bounds-change if the bounds-change is a result of
changing windowing-modes (and thus becoming organized).

This also records the original Task that a bounds-change
transaction was associated with along with the transaction.
This is needed anytime tasks are nested (eg. with home
task or with split-screen tasks).

Bug: 153579514
Test: See test entry for end of commit chain
Change-Id: If14ea07eca17ef9146537d5aae7122dd7c2dc045