[Feature Request] Support serialization of .aws/config file

[prestomation]

There are a number of tools that modify the .aws/config file on behalf of the user, either for ease of use or because they add their own properties to decorate a particular profile.

.aws/config file is an ini file which is not a standardized format, this means there is no guarantee that any particular ini parser will be fully compatible with the .aws/config file.

One real issue I've ran into in the rust ecosystem is that the service override functionality(like overriding a service endpoint) uses significant whitespace. This is not supported by rust's defacto ini crate rust-ini and it does not seem an easy path to get this added.

It seems it would be best if aws-config supported serializing profiles. This enable an application to modify the config file without fear of corrupting it as the SDK adds new features that potentially use ambiguous formats.