Support A11yInputFilter on multi-display

In order to support multi-display, some event handlers need to be
plural. Based on the characteristic of each event handler, only
the event handler that needs to deal with concurrent events from
different display needs multi-instance.

Test: a11y CTS & unit tests
Test: atest SystemUITests
Change-Id: I76379fb82aad09ee20609d81bd5b1dda15931905