feat: add IAM credentials discovery from process, metadata, and env #2004
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Problem
The identity LSP can only discover IAM credentials from the shared config files, temporary credentials cache, and STS AssumeRole calls. To reach feature parity with the Toolkit extensions and for potential auth migrations in the future, the identity LSP should also discover credentials from credentials processes, EC2 metadata, ECS metadata, and environment variables.
Solution
This is part of #1981.
License
By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.