Consider using VSCode's type command to improve multicursor support

[cvaldev]

Is your feature request related to a problem? Please describe.
There are many issues with the extension's poor multicursor support, but one of the most annoying ones is that it breaks snippets and auto-completion. On single cursor mode the extension passes over the text to the default: type command through TextEditor.insert(), this way vscode has control over the text input and can do stuff like auto-completion, snippet mode, closing brackets, etc.

Multiple cursors, however, are handled differently. vscode.TextEditorEdit.insert() is used instead, which doesn't allow vscode to do its regular stuff that it'd do on text insertion by default.

Describe the solution you'd like
Use the default: type command to process text insertion on multicursor mode like it is used on single cursor mode.

Describe alternatives you've considered
Here is a rudimentary prototype of my suggestion that solves issues like #4281, #4515, #4223.

if (this.vimState.isMultiCursor
      && otherTransformations[0]?.type === 'insertTextVSCode'
      && otherTransformations.every(t => t?.type === 'insertTextVSCode')) {

        const { text } = otherTransformations[0];
        vscode.commands.executeCommand('default:type', { text });

} else {
// The regular way we handle `otherTransformations`
}

VSCode's type command handles replicating what happens at the first cursor on the other cursors, and unless I'm wrong we can't do things like place x at cursor[0] and y at cursor[1] so there is no need to create an edit for each individual cursor as long as we know they're all the same.

I believe a better solution would be to introduce a new transformation (MulticursorInsert) that can know the cursor position like InsertTextTransformation, but is processed similarly to an InsertTextVSCodeTransformation.

Additional context
Before getting any further into it I'd like to know if this would be a welcomed change. I could submit a WIP PR if that's the case.

[alesso-x]

Another similar issue from 2017 #1946

[trkoch]

I too have observed a couple of issues and I'd really appreciate any improvements to the multicursor support. Can I help?

[J-Fields]

@cvaldev This seems very reasonable, though there could obviously be unforeseen consequences. A WIP pull request would be great, thanks as always for digging into these thorny issues!

Can I help?

Pull requests are always welcome, and I'm happy to provide guidance where it's needed. I agree multicursor support is a bit lacking @trkoch.