Add basic support for seek-based pagination to versions endpoint

[eth3lbert]

This PR is an improved implementation of #5302.
Add seek-based pagination support to versions endpoint with following:

• move versions to its own file
• To keep backward compatibility, paginate versions only if per_page is provided.
• Support sort query parameter to choose either sorting by date or semver .

For date sorting, we can perform sorting and pagination directly in the database. However, Heroku Postgres doesn't support the semver PG extension, so sorting and pagination for semver needs to be done on the app server.

Resolves #5292

[codecov]

Codecov Report

Attention: Patch coverage is 98.89807% with 4 lines in your changes are missing coverage. Please review.

Project coverage is 87.86%. Comparing base (5a5b2ab) to head (93e7362).
Report is 4 commits behind head on main.

Files	Patch %	Lines
src/controllers/krate/versions.rs	98.37%	3 Missing ⚠️
src/tests/routes/crates/versions/list.rs	99.43%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #8037      +/-   ##
==========================================
+ Coverage   87.73%   87.86%   +0.12%     
==========================================
  Files         271      272       +1     
  Lines       27145    27477     +332     
==========================================
+ Hits        23817    24143     +326     
- Misses       3328     3334       +6     

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[Turbo87]

one small bug, and a couple of comments, but overall this looks good to me. nice work! 👍

[Turbo87]

and in case you're wondering, I've rebased the branch on the current main :)

[eth3lbert]

feedback addressed. thanks for the review :)

diff 3f1a04e90057ae7f3714bcf3e6bd165223f00710..93e73621ccaac6b05afecc8d7488858aa84ae0b9

[Turbo87]

alright, let's give this a try! the test changes are all additive so I'm assuming the existing functionality won't break :)