Forwarding the rustls provider settings

[LecrisUT]

A nice reference for this is axum-server

tls-rustls = ["tls-rustls-no-provider", "rustls/aws-lc-rs"]
tls-rustls-no-provider = [...]

Such a design would make it easy for downstream to select the appropriate provider they need. Regarding hyper-rustls where this package is inheriting, I've opened an equivalent issue for a similar design, but even in their current form this can be configured with:

default = ["http-listener", "push-gateway", "_hyper-rustls-aws-lc-rs"]
_hyper-client = [
    "http-body-util",
    "hyper/client",
    "hyper-util/client",
    "hyper-util/http1",
    "hyper-util/client-legacy",
    "_hyper-rustls-no-provider",
]
_hyper-rustls-aws-lc-rs = ["hyper-rustls/aws-lc-rs"]
_hyper-rustls-no-provider = ["hyper-rustls/native-tokio", "hyper-rustls/http1", "hyper-rustls/tls12", "hyper-rustls/logging"]

As long as it is easy to detach the aws-lc-rs from the top-most default, that would help with forwarding this option through the dependency chain

[tobz]

Hey there! 👋🏻

I too am familiar with the pain of picking between different crypto provider backends in rustls all too well... 😅 I think your current PR (#516) is fine as an intermediate step, which I'll review/approve/merge shortly.

If you were interested in also trying to do something as you've described above, I'd be supportive of a PR going in that direction. 👍🏻