Add ability to block searches based on keywords

[ghost]

Checklist

• I made sure that there are no existing issues - open or closed - which I could contribute my information to.
• I have read the FAQ and my problem isn't listed.
• I'm aware that this is a request for NewPipe itself and that requests for adding a new service need to be made at NewPipeExtractor.
• I have taken the time to fill in all the required details. I understand that the feature request will be dismissed otherwise.
• This issue contains only one feature request.
• I have read and understood the contribution guidelines.

Feature description

This feature is related to issue 1815.

Currently, there is an option in settings to enable parental controls (called 'Restricted mode'). But this options hides many innocuous channels which makes it unuseful.

I suggest to add the ability to import a list of banned keywords. Keywords appearing in search string will be replaced by a space " ", therefore not showing any results.

Why do you want this feature?

Because the parental controls isn't very useful at the moment.

Additional information

No response