Custom user tools for text selection on page

[janvarev]

Is your feature request related to a problem? Please describe.
I wanna have custom tools for text selection on page to process them in my own way (rephrase, short analytics etc.). It'll be very cool!

Describe the solution you'd like
I see solution like this:

1. Add up to 3-10 (up to author) buttons in tools for text selection. They can look in menu just like neutral icon numbers 1,2,3 etc. - they are custom user tools.
2. In extension settings there are the same (3-10) number of options, where prompt for this tool is describen in format like
   Paraphrase this text: {selectionText}. Answer always in {prefLanguage} - with template vars in { } or something like that.
3. User tools can be enabled the same way as usual tools.

Hope it'll be not so hard to implement! Thanks a lot if you'll do it!

[janvarev]

Note: seems something similar was implemented in zwongstjude@8b30755