[Elasticsearch] Decouple code for versioned schema for repository and WIki on ruby side

For the original intention: see #328 (closed)

This implements #12548 (closed), the repository/wiki part.

What does this MR do?

1. Move repository related logic to the multi-indices architecture (i.e. ApplicationVersionedSearch and class/instance proxies).
2. Have indexer class iterate through all write targets and call the golang indexer.
3. Pass blob/commit label name table field_name_table and index name index_name to go indexer.

Does this MR meet the acceptance criteria?

Conformity

• [-] Changelog entry
• [-] Documentation created/updated or follow-up review issue created
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Database guides
• Separation of EE specific content

Performance and Testing

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.