Emily Matheys

If the feature is disabled then there is no `ClientConfig::builder()`, as that uses `ring` by default, another function is available. `ClientConfig::builder_with_provider()`, allowing usage of any provider the user wishes, notable...

@djc I have not timed them both, but I feel that `ring` takes _ages_ to compile, and if `aws-lc-rs` is faster, that might be a major factor in my decision...