resourcemanager: initialize aidl parcels with defaults

Addresses a TODO to set the default enum values for aidl structures.
Since, the usage of these parcelable structures are limited internally,
there is no functionality change associated with this change.

Bug: 289097671
Test: atest android.media.misc.cts.ResourceManagerTest
      atest android.media.misc.cts.ResourceManagerMultiTest
      /data/nativetest64/ResourceManagerService_test/ResourceManagerService_test
      /data/nativetest64/ResourceObserverService_test/ResourceObserverService_test
Change-Id: I0eda837cc0c2c7dd5efebce957959a1dab8ebf7e