Source versioning, validation and indexing update (WIP)

[strogonoff]

• Captures dataset version (Git commit hash) and indexing timestamp as part of indexed item information in RefData
• Implements (better) data validation during indexing. It loads the data through Relaton’s Pydantic models, and when storing the data in RefData.body it uses the BibliographicItem model’s dict() output.
• When full data source is indexed, indexing now happens not in a single transaction, so for large sources updates take effect faster
• Adds a public page listing indexed sources, their latest indexing timestamp

[strogonoff]

I believe this should be ready, needs some more testing…

[strogonoff]

@stefanomunarini it looks like this one should also be rebased (?)

There’s more commits here than in #29.

[strogonoff]

Attempted to fix conflicts with our main branch.