Remove async-trait dependency?

[FalkWoldmann]

Hi! I've seen that the async-trait dependency is used for some traits that are public. Would you consider it a good idea to use the native async trait functionality before going GA? I could open a PR if desired

[cijothomas]

This should already be the case. We recently removed async-trait dependency. Happy to accept a PR if there are still leftovers!

[FalkWoldmann]

I see that asyn-trait is still used for HttpClient. Unfortunately, we cannot just remove the dependency, since stable Rust does not support dynamic dispatch on async traits. Having a very brief look at the code, we could:

1. Try to fully rely on static dispatch, thus making the code faster, but the code potentially harder to read.
2. Using a enum_dispatch approach by replacing the dyn HttpClient references with some enum value, which will be more performant than the status quo, but slightly slower than option 1.

Since I am not familiar with the codebase, I may have missed some crucial information. I'm looking forward to some feedback :)

Cheers

[cijothomas]

@gruebel also mentioned the same limitations. I don't have an immediate answer. If you can explore option1, happy to review a PR (even draft one).