Add cop to detect complex indexes without names

What does this MR do?

Relates to: #229852 (closed)

Add a new cop that checks if migrations concurrently add a new index with an options hash, but don't give an explicit name. Rails ignores the options hash when generating the index name, using only the table and column names. Since add_concurrent_index skips the index creation when an index with matching name exists, this leads to issues when two indexes cover the same columns but with different options.

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• Documentation (if required)
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Availability and Testing

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.
• Informed Infrastructure department of a default or new setting change, if applicable per definition of done

Security

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