feat(#373): merge-contacts action

[kennsippell]

Description

#373

This adds new action cht merge-contacts. The change proposes to:

• Move the code for move-contacts into a library lib/hierarchy-operations with interfaces move and merge
• Parameterize the move-contacts code changing logic for: input validation, deletes the top-level contact, changes how lineages are updated, and adds report reassignment. All else remains unaltered.

Handles reports and contacts only. Unclear what other doc types I should be worried about.

Things I still need to do. Thinking to do them in their own PRs.

• Add an option which deletes the primary contact so resulting areas don't have two duplicates contacts
• Update upload-docs so it handles user accounts when deleting a document
• Add some metadata onto documents when they get moved

Code review items

• Readable: Concise, well named, follows the style guide, documented if necessary.
• Documented: Configuration and user documentation on cht-docs
• Tested: Unit and/or integration tests where appropriate
• Backwards compatible: Works with existing data and configuration. Any breaking changes documented in the release notes.

License

The software is provided under AGPL-3.0. Contributions to this project are accepted under the same license.

[kennsippell]

Struggling with the interface here. I've gone through:

• sources/destination
• remove/keep
• losers/winner

Welcome suggestions that seem intuitive.