feat: add duplicate document action

[nkgentile]

Adds a custom document action to facilitate duplicating a localized document, its translations, and the underlying metadata document.

Things to review:

• Naming
• Whether to include in plugin by default or opt-in
• handle and using the document store in general
• Patching metadata document with document store instead of client?

[SimeonGriggs]

Huge! Thanks!