Make Keyword Filter to skip an item instead of emptying the value

@jabberwooki, thank you for the solution in #7. It worked beautiful for my use case.

On the field to be filtered, just add 2 plugins :
- add the TEXT / keyword filter plugin first,
- then add the FILTER / required plugin.

I plan to work on this, have drafted some locally, but first ✨ KeywordFilter: more config pre-processing from form validation to tamper execution Active needs to land.

✨ KeywordFilter: more config pre-processing from form validation to tamper execution Active is done! So here is a MR that will make KeywordFilter to throw a SkipTamperItemException instead of emptying a value if the data does not contain one of the configured keywords.

Hopefully, the MR passes tests.

I merged the changes!

Automatically closed - issue fixed for 2 weeks with no activity.