Restrict proxies for displays owned by the caller

A virtual device should only be allowed to proxy displays it owns. This checks
the available displays and compares the owners to the calling uid used
when registering a proxy.

Test: atest AccessibilityDisplayProxyTest, manual with Exo
Bug: 280661435
Change-Id: I7f7a4d5c1cb5510410e5b8d5348d2ce67b30af4b