Rename "Version" to "Branch"

[bctcvai]

Renaming the database object and public facing accesses will help clean up literature about utilizing the concept in workflows.

Actions:

• Rename Version database object to Branch
• Evaluate whether mapping into ES should change (e.g. whether _annotation_version should be renamed to _annotation_branch).
  • Given its a buried term, we might be able to just leave it, and adjust the mapping. Downside is the query builder exposes the system's privates ("_" fields), resulting in possible future confusion.
  • Coordinate migration of this field in ES to execution of migration of legacy projects to utilizing elemental_id.
• Deprecate existing "version" accessor in rest API. Add new "branch" parameter with equivalent behavior.