MediaProfiles: expose CamcorderProfile objects for clients

Previously fields were retrieved via a central get(id1, id2, name) getter
that did not scale well to multiple encoder profiles for a single
object.

Expose the sub-objects directly with proper getters.

Bug: 171673898
Test: atest CamcorderProfileTest
Change-Id: Ia8e2451f3d4fe2c013da69aa6b26e60d66598a32