* [#367] Enhanced multi-lang `AWSCredentialsProvider=...` decoder and construction.
+ added support for external ids (issue #367)
+ added support for endpoint+region (e.g., STS via VPC)
* Multiple multi-lang edits to introduce logging and additional tests.
+ added `ENDPOINT_REGION` nested key for a simpler Cx experience
+ deduplicated, and improved, logic w.r.t. CredentialsProvider
construction to NOT swallow Exceptions
* Relocated `multilang.properties` from `main/resources` to `test/resources`
