Braille: Allow sticky USB permission

Once permission is granted to a Braille device, record it's serial
number so it can be automatically granted permission again when it's
plugged in again.

This also maintains USB permission when exiting SUW.

Bug: b/423932763
Test: AccessibilityServiceConnectionTest
Flag: com.android.server.accessibility.enable_braille_suw_immediate_connections
Change-Id: Ib9bab7fcf2789368d5e685d0996e8c9751726685