Implement API call to upload and store patches being tested in kernelci storage

To test patches in KernelCI Maestro we need to make such patch stored long term in a secure, public storage provided by KernelCI infrastructure.
Keeping patch accessible important to review possible regressions by third parties and to be able to retest it in the future.
We need to develop API calls that will do basic verification (including possible security checks) and store the patch in the KernelCI storage.
We need to keep also checksum as well in case we might reuse already stored patch.

## Requirements

- [ ] Authentication / Authorization, not all users should be able to store patches
- [ ] API endpoint to receive patch
- [ ] Verify patch
- [ ] Generate checksum
- [ ] Verify checksum if already stored
- [ ] Store patch information in database (creation date, checksum, patch name, creator)
- [ ] Store patch in KernelCI storage and return URL

No files, tests, or entry points are named. Start by locating the existing API, authentication and authorization, database, and KernelCI storage integration entry points, then trace how uploaded artifacts are handled. Done means the listed endpoint, verification, checksum reuse, metadata persistence, secure storage, and returned URL requirements are implemented and tested.

Written by the indexing model from the issue text.