Can rustls backend feature flags be consolidated?

[paulcdejean]

Right now there's separate rustls backend feature flags for "quinn only" and for "quinn + rustls." Sorta? I'm not completely sure.

There is rustls-aws-lc-rs-fips and aws-lc-rs-fips
There is rustls-aws-lc-rs and aws-lc-rs
There is rustls-ring and ring

It would make navigating the features list much simplier if these were squished together. However if there's some use case for enabling ring but not rustls-ring for example, then maybe someone with that use case might have a suggestion for how this can be simplified without breaking their use case.

[djc]

I think I put this in place, not because I have a clear use case but because it made sense for the implementation. I don't see many downsides -- we can just downplay the existence of the non-rustls features, which are arguably pretty niche.