Add Display flag "FLAG_STEAL_TOP_FOCUS_DISABLED"

The top focused display is the display that receives untargeted input.
I.e. input events without a specific displayId. The flag declares that a display
can not become the top focused display. Such a display will only receive input
events that are targeted at it.

Test: atest WindowFocusTest
Bug: 262700485
Change-Id: I8d40b20363595d11de1fadb3e895ea72f57a3a27