* iam_group: (integration tests) migrate tests to module_defaults
* iam_group: (integration tests) migrate to using temporary user and group with {{ resource_prefix }}
* iam_group: (integration tests) fix test, checking the return values
* iam_group: (integration tests) Add some more tests around the behaviour of 'changed'
* iam_group: (docs) Update documentation of iam_group return value
* Update AWS testing policies to enable group/user management
