ValidationSummary: add accessibility support #15760

Job	Run time
Build	3m 33s
Check if all tests should run	3s
ui.grid-shadow-dom	7m 2s
ui-shadow-dom	4m 40s
ui.scheduler-shadow-dom	7m 4s
ui.widgets-shadow-dom	9m 20s
ui.editors-shadow-dom	6m 33s
Constel misc-no-csp	5m 47s
Constel ui	5m 7s
Constel ui.widgets-no-csp	13m 49s
Constel ui.scheduler	6m 17s
Constel misc	4m 6s
Constel ui.editors	4m 40s
Constel ui.scheduler-US/Pacific	7m 52s
Constel ui.grid	5m 22s
Constel export	3m 50s
Send notifications	0s
	1h 35m 5s

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