[8.19](backport #47260) Add AWS auth method for cel and httpjson inputs

[mergify]

Proposed commit message

Add a new auth method for cel and httpjson that wraps the aws v4 signer.

As discussed here this PR introduces an new auth method that can be used in cel and httpjson integrations.

This AWS auth method is implemented by creating an HTTP transport that wraps the transport of the client, uses a configuration, AWS credentials, and v4 signer, and signs the request just before passing it to the next (actual) HTTP transport.

example of cel and httpjson configs that uses the aws auth:

### cel
config_version: 2
interval: {{interval}}
auth.aws:
  access_key_id: {{access_key_id}}
  secret_access_key: {{secret_access_key}}

### cel
config_version: 2
interval: {{interval}}
auth.aws:
  role_arn: {{role_arn}}
  external_id: {{external_id}}

### httpjson
config_version: "2"
interval: {{interval}}
auth.aws:
  role_arn: {{role_arn}}
  external_id: {{external_id}}

The auth method config can be initialized with static credentials as well as assume role arn and every other available config in ConfigAWS.

The service name and default region can be configured or inferred from the URL of the request.

When using this method, the integration (cel or httpjson file) does not need to re-implement the aws sing process inside the file, while at the same time having the singer as http.Transport, offers some advantages (described here; like enabling an integration using all available aws auth methods based on user config with a single cel/httpjson file) and will enable the cloud connectors project to be expanded to other aws integrations (cloud connector specific changes will be introduced in a later PR).

Checklist

• My code follows the style guidelines of this project
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• I have made corresponding change to the default configuration files
• I have added tests that prove my fix is effective or that my feature works
• I have added an entry in ./changelog/fragments using the changelog tool.

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This is an automatic backport of pull request #47260 done by [Mergify](https://mergify.com).

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[olegsu]

more context #49956 (comment)