Separate out create/delete iam role functions into lib.

[DailyDreaming]

Changelog Entry

To be copied to the draft changelog by merger:

• Separate out create/delete iam role functions into lib.

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    contrib/admin/test-pr otheruser theirbranchname issues/XXXX-fix-the-thing
    

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[adamnovak]

This looks like the actual changes are good, but I think we probably want to have docstrings to go with our new API we're building.

[adamnovak]

Even though delete_iam_instance_profile doesn't get a docstring, I think this is probably good now.