Implements first iteration of multi diff editors.

[hediet]

Tasks left:

• More performant scrolling
• Collapsing files
• adding/removing files

Fixes #179000

[bpasero]

I was only looking at a few files, not the larger pieces and left some feedback. I am adding @lramos15 for reviewing the editor resolver changes.

[lramos15]

I'm guessing there is, but just for my understanding is there a reasoning for not making this a one off editor type like Chat, Search, the Perf graph, etc instead of adding an entire new editor type that my guess is won't be implemented elsehwere

[hediet]

I'm guessing there is, but just for my understanding is there a reasoning for not making this a one off editor type like Chat, Search, the Perf graph, etc instead of adding an entire new editor type that my guess is won't be implemented elsehwere

I was wondering the same. Let's start with this and refactor later.
Because the widget lives separately, it should be easy to address this later.

issues resolved

[IllusionMH]

Is it only for Git (VCS) view for now (at least this is my impression after glancing over this PR code)?
I can't find command that would allow me to use it to diff 2 folders. Are there plans to support folders diff?
Similar to how keybinding below allows to quickly diff files(or open editors)

    {
        "key": "ctrl+d",
        "command": "compareSelected",
        "when": "listDoubleSelection && activeViewlet == 'workbench.view.explorer'"
    },

[hediet]

Is it only for Git (VCS) view for now (at least this is my impression after glancing over this PR code)?

We will slowly integrate it into other features as well.

I can't find command that would allow me to use it to diff 2 folders. Are there plans to support folders diff?

This is out of scope for this feature, but maybe this can be implemented by an extension.