Filter modifiers

[AndreasArvidsson]

Fixes #1005
Fixes #1006

Checklist

• Add filter modifiers
• "every line" should include empty and whitespace lines
• I have added tests

[pokey]

Super cool to see that this was actually as trivial as we hoped. Great sign. Left a couple minor comments

[pokey]

Ok I have an alternative idea: how about we just create a meta-modifier called "only" that can accept any scope. It tries to expand to the scope. If it fails, it returns []. If it succeeds it just returns the original target [target]. If user wants expansion as well they can chain normal scope after. So then eg we could say "take only chars" and it would give you the cursors that contain or are adjacent to a non-whitespace char, which seems more useful than "content" anyway I think

It also might be useful to have a forgiving version of containing scope. Could be a flag on either usual containing scope or on this modifier. As mentioned above it can be accomplished by chaining: "funk only funks", so maybe not that important 🤷‍♂️

Should be trivial to impl, tho will be better with plurals and proper scope handlers

But I'm hesitant to introduce the stuff here if we'll replace it with this more powerful version

[AndreasArvidsson]

It is an interesting idea. Maybe we should do that in addition to the ones we have here? In some sense I think that content fits my mental image better than only characters. We can always do a follow up pr and add that if we want?

[pokey]

I'm just hesitant to add something to the csv if we aren't sure about it

[AndreasArvidsson]

I think we should add those in addition and keep the three added here.

[pokey]

Let's chat tomorrow

[AndreasArvidsson]

@pokey Updated. I'm still a bit hesitant if we should add the word "keep" before the default spoken form? This is really only a modifier for multiple cursors so maybe it's fine to be a bit verbose?
If you agree please go ahead and make that change otherwise I'm happy and we can merge this.