Calls from default argument values show inconsistent caller information about rotoscope

[dylanahsmith]

This wouldn't be a problem if we weren't trying to surface the caller entity. We could use rb_profile_frames to get efficiently get the caller method name, which we already do to accurately get the caller file path.

Previously we were deriving the caller component from the caller entity, but now we can do that from the caller file path. We won't always have a caller entity anyways for anonymous classes/modules or from calls in blocks.