`data_column` parameter: use `column_names` metadata if present

[bernt-matthias]

trafficstars

makes data_column work for all data types setting column_names and still fallback to try to take the first line (tab separated). The later is necessary for tabular which does not set the column names metadata.

fixes: https://github.com/galaxyproject/galaxy/issues/17468

How to test the changes?

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• [x] I've included appropriate automated tests.
• [ ] This is a refactoring of components with existing test coverage.
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  1. [add testing steps and prerequisites here if you didn't write automated tests covering all your changes]

License

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