Rustus has been rewritten from scratch

[s3rius]

This PR is a complete rewrite of Rustus from the ground up.

I tried to reach actix team that they have memory leaks somewhere inside. I made lots of tweaks and changes, but the memory usage was still huge. Later I found out that axum framework can produce almost the same throughput, but it's memory usage is much effective. So, I decided to switch to it.

To decrease memory usage also, we removed all boxes from the app's state, now we depend on nightly channel to use non-boxed async function in traits. Ref: https://github.com/rust-lang/rust/pull/115822.

Here's the transition roadmap:

• [x] Axum server
• [x] File data storage
• [x] Hybrid-S3 data storage
• [x] File info storage
• [x] Redis info storage
• [ ] DB info storage
• [x] All existing notifiers
• [ ] Tests
• [ ] Fixed docs

[s3rius]

The core functionality is ready. Everything what's left, will be added within subsequent PRs.