Guide feature request: see who's editing theme files and/or prevent multiple access

Quick overview of feature request

As a Guide Admin, I'd like to be warned when someone else is editing the same theme file(s), or be stopped from accessing the file in the first place (identical to Zendesk Explore not allowing us to edit a report someone's already editing).

What problem do you see this solving?

Multiple people editing the same files, saving, and work being unnecessarily deleted.

When was the last time you were affected by this lack of functionality, or specific tool?

Today.

What happened?

A colleague was editing the script.js file I had been editing and I had to restart my computer. Because he saved his work, my version was not stored.

How often does this problem occur and how does this impact your business?

Not very often.

Are you currently using a workaround to solve this problem?

We ask in Slack if anyone's editing anything, but sometimes it's natural to just go ahead with the editing and forget about asking.

What would be your ideal solution to this problem? How would it work or function?

Guide Admin 1 (A1) is editing one or more theme files (script.js, style.css, requests.hbs, etc.), and Guide Admin 2 (A2) the system could either:

1. Prevent A2 from accessing/opening the file by showing him a warning that A1 is already editing the file; or 
2. Allow A2 to open the file but show a warning to both users that the other is viewing/editing the file; and/or
3. Allow A1 and A2 to edit the file simultaneously by collaborating and saving all changes in real time (as in Google Docs, for example)

Thanks!