Add Date Modified and Date Created sorting for repositories

[fabiovincenzi]

Context

The repo list UI has a sort dropdown that previously included "Date Modified" and "Date Created" options. These are being removed as part of the server-side pagination in #1464 because the fields lastModified and dateCreated don't exist on the Repo model, sorting fell back silently to alphabetical order.

What needs to be done

• Add lastModified and dateCreated fields to the Repo model
• Populate them on repo creation and update
• Add them to the sortBy allowlist in the repo route
• Re-add the options to the Filtering dropdown in the UI

Migration considerations

• Existing DB records won't have these fields
• Need a migration strategy for both MongoDB and NeDB
• Should consider backwards compatibility / ability to roll back
• kriswest noted: dates could potentially be extracted from existing logs

[jescalada]

As you mentioned, backward compatibility is a must here - we probably shouldn't be breaking the API when adding a new endpoint might do the trick. Likewise with the DB, filling in the blanks like what we did with repo URLs in #1043 might be the best: just automatically fixing those up on startup so users don't need to worry about migrations.

This ought to be added in 2.1 (or 2.2) rather than being forced to cut a 3.0 just for this single, potentially breaking change.

Pinging @kriswest for thoughts on this 🤔

[kriswest]

If we can migrate forwards and backwards to/from the next/previous version, and we're not breaking any existing API calls, then I think this probably non-breaking and can go in a minor release. We may need to add something to track and perform (DB) migrations in order to achieve it (i.e. add a DB table that tracks whether a migration has been run) - that would be a good facility for us to have anyway and may help us to implement a variety of other planned features that will affect the data model and prevent those also forcing a major release. There are various libs out there that implement migration like behaviour, but its also easy enough to roll your own.