Issue 9656 Raise an error when check_cols has duplicated values

[ariosramirez]

resolves #9656

Problem

Currently, the check strategy for Snapshots does not throw an error if there are duplicate column names specified in the check_cols config, and accidentally specifying a column twice results in a record being inserted even if none of the column values changed.

Problem described in #9656 (comment)

Solution

This PR adds validation to detect duplicate column names in the check_cols configuration of a snapshot. It raises an error if duplicates are found.

Checklist

• I have read the contributing guide and understand what's expected of me
• I have run this code in development and it appears to resolve the stated issue
• This PR includes tests, or tests are not required/relevant for this PR
• This PR has no interface changes (e.g. macros, cli, logs, json artifacts, config files, adapter interface, etc) or this PR has already received feedback and approval from Product or DX
• This PR includes type annotations for new and modified functions

[github-actions]

Thank you for your pull request! We could not find a changelog entry for this change. For details on how to document a change, see the contributing guide.

[github-actions]

Thank you for your pull request! We could not find a changelog entry for this change. For details on how to document a change, see the contributing guide.