Add line numeration to the validators.

[BlitzOffline]

So when I have an invalid file and I put it thru one of the validators I get an error similar to this:

Parsing error on line 22, column 55: Expected "=", [ \t] or [A-Za-z0-9_-] but "." found.

The problem is then I have to go and find out which is the 22nd line and since they're not marked in the toolbox, I either have to open a new page in a text editor that does have line numeration and paste it there so I can see it or I have to count the lines myself. It would be nice if there would be a line numeration directly embedded in the page. Something like this:

[Starmism]

So this is quite hard to do as the current implementation uses a library called react-simple-code-editor, which, as the name implies, is quite simple and lacks a line number implementation. We'd need to swap to a new code editor library to add this. One I've seen suggested a lot is CodeMirror, but I'm not super familiar with the ecosystem in this area.