Create eslint plugin to only allow DOMContentLoaded in imported page modules

With the recent dispatcher refactor I have noticed that debugging these imported modules can get tricky. As a result, I would like to propose to the team that do not allow DOMContentLoaded for any scripts outside of the pages/ modules.

I propose for us to write a simple eslint plugin to make this check. We will need to continue refactoring existing use cases of DOMContentLoaded (or add some kind of whitelist) before we add this eslint plugin to gitlab