feat: Add `credentials_arn` to support ECR pull through cache

[JoseAlvarezSonos]

Description

This feature PR adds the ability to pass a credentials_arn to the registry_pull_through_cache_rules variable, to allow to use this new field for pull through caches.

Motivation and Context

Since November 2023, ECR supports new upstream registries as pull through cache, including Dockerhub and GHCR. To use these new upstream registries, it's required to use credentials for the respective registries. AWS added a feature of providing a Secret Manager resource ARN to the ECR pull through cache rule to rely on this credentials. Along side this, the terraform-provider-aws added the same capabilities to the aws_ecr_pull_through_cache_rule resource.

Breaking Changes

This requires an update of the aws provider to >= 5.37 (previously >= 4.20). But there isn't any breaking change to update to this version.

How Has This Been Tested?

• [x] I have updated at least one of the examples/* to demonstrate and validate my change(s)
• [x] I have tested and validated these changes using one or more of the provided examples/* projects

We are using our fork to make sure that it works and added all the required docs and examples to this repo as well.

[shivanand-deriv]

+1

[bryantbiggs]

for the example? we don't usually enforce this for examples and just stick with the default commercial regions. the module source code we absolutely use the data sources to infer the correct partition, region, etc.

[antonbabenko]

@bryantbiggs I looked in the wrong place :) Approved now

[antonbabenko]

This PR is included in version 2.1.0 :tada:

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