Define an abstract data api

[jchartrand]

Move all of the data calls (mongo CRUD) to a well defined (OpenAPI/Swagger) RESTful interface, so that others can more easily understand how to substitute their own calls or backends.

Also, right now there is at least one LEF coded call that uses local Payload libraries - it should use the api endpoints like other LEF calls:

https://github.com/digitalcredentials/admin-dashboard/blob/03428e947ae7e6f20d4f2121155b1ec73c8d921e/services/payload/src/payload.config.ts#L97-L112

Aside from those api calls, there are also payload specific calls that are buried in the payload front end code ( like for creating new batches, users, templates). These should ideally be extracted to their clearly defined API, alongside every other api call.