HTTP Connectors Refactor pt.1 - Laying the groundwork (#1144)

* refactor: HttpSettings, HttpConnection location
update: replace timeout::Settings with TimeoutConfig
add: HttpConnector to aws_types::Config and Builder
refactor: divide default_provider.rs modules into separate files

* add: missing copyright headers

* add: missing http_connector accessor to Config

* remove: unused import

* update: undo changes to aws_config::connector module
remove: impl Default for HttpConnector

* update: CHANGELOG.next.toml