Change profile validation to enforce case insensitive unique rule names

[dmjb]

Previously, minder required rule names to be unique within an entity type, but did so in a case-sensitive manner. Minder's API expects rule names to be unique in a case-insensitive manner. This changes the validation logic to prevent new rule instances from being created if they are not unique in a case insensitive manner.

Summary

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Fixes #(related issue)

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• Reviewed my own code for quality and clarity.
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[coveralls]

coverage: 54.364% (-0.005%) from 54.369%
when pulling 234372a on validate-case-insensitive-names
into 66f213c on main.