Ignore empty lines when uncommenting code

[jsjtxietian]

Fixes #81474

[jsjtxietian]

I did some test with vscode and have updated my code a little bit according to vscode's default behaviour, the code works this way now:

When commenting/uncommenting code, empty lines do not affect godot's decision of whether the selected code is commented or not, unless they are all empty lines, in that case I treat them as uncommented code.

[jsjtxietian]

Hi @Paulb23
If I get your example right, the origin example should look like this, one caret with a selection on lines 1-3, the second caret is on line 3:

After I commented in the current stable 4.1, it became this, looks like both carets collapsed:

And in the godot with my commit, it became this：

The caret's position changed, yes, but the master version doest't seem working correctly too.

[akien-mga]

Thanks!