Various minor suggestions to improve/align CIViC Data example

[mbrush]

Feedback based on the tr-statement-inline.yaml example at commit b546010.

1. I don’t think TRStatement.is_reported_in is the right attribute for capturing the publication supporting a CIViC EID record. This would imply that the Statement expressed in the CIViC EID record (that study result X represents level Y evidence supporting proposition Z) was reported in that paper - which is not the case. Rather, we should use 'has evidence from source'.
2. Contribution.activity values used in the data sound like roles. Given that we have renamed this attribute 'activity', we should name Coded values of this attributes accordingly (e.g. 'approval', not 'approver'), 'acceptance' not 'accepted' or 'acceptor')
3. TRStatement.evidence_level may not be the right attribute, given that the values here sound like evidence types. While it may sound radical, consider splitting the A-E levels (which we could capture using evidence_level) from the corresponding evidence types (which we could capture using has_evidence_of_type) . . . I know there is a 1:1 here, but IMO it fits the VA model better, and makes the data easier to understand.