Add API routes to request multiple of an item

[Geometrically]

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[Aeledfyr]

One, fix the failing checks & run cargo fmt.

I'm not sure about moving the version routes to the api root; It makes sense, but then it makes less sense to have mod/{mod_id}/versions return a populated list of versions rather than a list of ids.

The routes for getting a list of entries seem useful, but is the naming the best? It may become confusing to have both /api/v1/mod and /api/v1/mods as routes, one that searches and one that requests by id.

[Geometrically]

One, fix the failing checks & run cargo fmt.

I'm not sure about moving the version routes to the api root; It makes sense, but then it makes less sense to have mod/{mod_id}/versions return a populated list of versions rather than a list of ids.

The routes for getting a list of entries seem useful, but is the naming the best? It may become confusing to have both /api/v1/mod and /api/v1/mods as routes, one that searches and one that requests by id.

Fixed failing checks

The reason why it won't return all the versions is because we have the get multiple versions route, so the user can decide what versions they actually need/want.

It might be confusing, but that is what documentation is for. I don't know a better way of doing it

[Aeledfyr]

Batched database queries should be an order of magnitude faster, so we should at least try them. If it doesn't work out then what we have may be good enough, but it seems like it should be easy enough to implement.

[Aeledfyr]

Still a few things left, but it's almost done. Now it's mostly just the array types for the batch get routes and database methods.