Added WebIdentityTokenCredentialsProvider in AWS Credentials Provider…

[shashisingh]

Added WebIdentityTokenCredentialsProvider in AWS Credentials Provider Chain. This is required for supporting pod level IAM roles for service accounts (IRSA).

Support for AWS IRSA for druid pods in a kubernetes cluster

I have added WebIdentityTokenCredentialsProvider credentials provider in the provider chain.

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This PR has:

• been self-reviewed.
• added documentation for new or modified features or behaviors.
• added Javadocs for most classes and all non-trivial methods. Linked related entities via Javadoc links.
• added or updated version, license, or notice information in licenses.yaml
• added comments explaining the "why" and the intent of the code wherever would not be obvious for an unfamiliar reader.
• added unit tests or modified existing tests to cover new code paths.
• added integration tests.
• been tested in a test Druid cluster.

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Key changed/added classes in this PR

• org.apache.druid.common.aws.AWSCredentialsUtils

[suneet-s]

It appears this support was added in #10541