Adds 'additional_settings' option to configure the underlying AWS client

[andsel]

Release notes

Add additional_settings option to fine-grain configuration of AWS client

What does this PR do?

Introduce the option additional_settings which is a map that, once the keys are symbolized and boolean strings becomes boolean values, is passed down to the creation of AWS SQS client.

Why is it important/What is the impact to the user?

This option permit the user to fine-grain configuring the client, for example to enable debugging logs at wire level, asin:

additional_settings => {
    http_wire_trace => true
}

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 (and/or docker env variables)
• I have added tests that prove my fix is effective or that my feature works

Author's Checklist

• Build the gem and try a run against SQS

How to test this PR locally

• build the gem gem build and install on a local Logstash instance
• grab account access key and token for an AWS account
• create an SQS
• setup an input like:

input {
  sqs {
    queue => "<your queue name>"
    region => "<aws_region>"
    endpoint => "https://<aws_region>.amazonaws.com/<nnn>/<your queue name>"
    access_key_id => "aws_key"
    secret_access_key => "secret 1"
    role_arn => "arn:aws:iam::<nnn>:role/ElasticDeveloper"
    session_token => "secret 2" 

    additional_settings => {
      http_wire_trace => true
    }
  }
}  

Related issues

• Closes: Improve Debug Logging #59

[kares]

LGTM,

there's the same setting in S3 input and implementation wise it does the same logic of casting true/false values