Do not send update exclusion updates when rects didn't change

Additionally, avoid sending the same MSG_SYSTEM_GESTURE_EXCLUSION_CHANGED
unecessarily

Bug: 388231176
Test: manual - perfetto: check how many calls are now skipped
Test: ViewRootTectTrackerTest
Test: SystemGestureExclusionRectsTest
Flag: com.android.window.flags.reduce_changed_exclusion_rects_msgs
Change-Id: I63a6ad7956df6ebebec83a651acf7f80cdfa49a1