Create Profile File Provider for Region (#682)

* Create Profile File Provider for Region

As part of this work, I unified handling of provider configuration into `ProviderConfig`. This simplifies and removes boilerplate from the credential provider builders.

* Fix profile name bug, add test

* More cleanups around connection management

* Lots of cleanups around connector handling and crate features

* Update Changelog

* Remove unecessary sleep module

* Add builder convenience method

* CR feedback

* Update aws/rust-runtime/aws-config/src/default_provider.rs

Co-authored-by: John DiSanti <jdisanti@amazon.com>

Co-authored-by: John DiSanti <jdisanti@amazon.com>