Move the core computer control logic to system server

The virtual device is created and managed within VDM but still owned
by the caller.

The app process is provided a minimal Binder interface to perform
limited safe operations on the virtual device, displays, and session.

Fix: 432679227
Test: atest
Flag: android.companion.virtualdevice.flags.computer_control_access

Change-Id: I339337f7d1f222fb66c42fcbc1d71240ec08a8d1