Default crypto library is aws-lc

[davide-baldo]

The current default crypto library is aes-gcm since it has a broader compatibility without any additional dependencies, but it's also slower and different from release builds which are built using aws-lc.
The default features in command should switch to aws-lc, and we should print a warning when compiling on a non-supported platform (linux/mac amd64/aarch64), advising the user of the possibility of using rust-crypto or adding the extra dependencies.
Also, the CI will be using the default features rather than manually specifying them in multiple locations.

[SanjoDeundiak]

Ideal case: we use aws-lc by default and automatically switch to `rust-crypto if it's available. Not sure that's possible

[davide-baldo]

Do you mean switching to rust-crypto automatically when aws-lc dependencies are not available?

[SanjoDeundiak]

Yes

[davide-baldo]

I don't think it would be ideal, having fixed dependencies is a plus for me. Introducing extra complexity and brittleness to better handle uncommon builds (non linux/macos, non amd64/aarch64) is not a worth tradeoff in my view.
In platforms where aws-lc is not fully supported, the user would still have the option of introducing the extra dependencies to build the bindings, and retaining the performance benefits of aws-lc.
If we automatically ""downgrade"" the dependency, the user might never know this was an option, or even worse, it may happen to us after a CI upgrade and we might not even notice it.