Add the ability to pass in an EC2 IAM role to launch with

The EC2 instance being launched should be able to take on a defined instance role if one is provided: https://docs.ansible.com/ansible/latest/collections/amazon/aws/ec2_instance_module.html#parameter-instance_role

Start by tracing the EC2 launch entry point in this plugin and compare its options with the referenced Ansible ec2_instance_module parameter, instance_role. Done means a supplied IAM role is applied to the launched instance, while launches without one continue to work; add or update the relevant tests after locating them.

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