Add a `cmd accessibility` shell command to check HIDRAW access.

This is used by GTS to confirm that system_server has access to interact
with hidraw nodes, as needed for the BrailleDisplayController API.

Bug: 311783331
Test: atest GtsAccessibilityTestCases
Change-Id: Iefef117cf916f7e9e2de2f52a6fa38ba355becb6