Use consistent column names with separators when speaking about different representations of the same term

e.g.

sex.name
sex.accession

cellosaurus.name
cellosaurus.accession

This will help tremendously when converting to yaml, json to identify which columns belong together.

No file or test is identified in the issue. Review the repository's current metadata column definitions and find terms with multiple representations, then compare their existing naming conventions. Done means related columns use consistent separators so YAML and JSON conversion clearly groups them.

Written by the indexing model from the issue text.