Flag for moving VIMS init resource work

VoiceInteractionManagerService start currently blocks boot for >100ms
while it loads resources from AGSA. This service isn't needed for other
downstream service inits and isn't accessed until users are starting, so
this resource work can be done in a separate thread to avoid blocking
the boot critical path.

Test: presubmit
Bug: 406841419
Flag: android.server.voiceinteractionmanagerservice_get_resources_in_init_thread
Change-Id: I8ff127ec26318548da6d0590c43a45002e1bd8a2