Add endpoint to check if a specific problem is solved by a user and return its last solved timestamp

[Abhi-tech-09]

Hello! 👋🏻
First off, great work on this API.

I am preparing for OA's and DSA rounds and I have been using these company-tagged problem lists available on github to carry out my preparation. The sheets have around 100-200 problems and problems are similar across different companies.
I’m trying to build a little script that:

1. Takes a list of problem slugs (like two-sum, add-two-numbers, etc.) or problem ID's.
2. Checks if I’ve solved them.
3. Most importantly, tells me when I last solved them.

Right now, you have a GET /:username/acSubmission endpoint that fetches latest 20 AC submissions but the filter param is ineffective after 20.

Would it be possible to add a simple endpoint like:
GET /:username/check?titleSlug=two-sum

That could return something like:

{
  "solved": true,
  "lastSolved": "2024-06-10T09:15:00Z",
  "daysAgo": 7
}

This would allow me to build a small "problem revision tracker" that can identify problems I solved several months ago and may need to revisit before interviews.

If this is something you'd consider adding, I'd be happy to help with the implementation or contribute a PR.

Thanks