editor-plugins: add hashbang line highlighting

[lucab]

This adds supports for highlighting an hashbang line as a comment, in vscode and in highlight.js.

• Tests added for any new code
• Documentation added for any new functionality
• Entries added to the respective CHANGELOG.md for any new functionality
• Feature table on README.md updated for any listed functionality

[bugarela]

✨

[lucab]

I didn't touch Vim and Emacs here. I'm not very familiar with their grammars definition, but for both I didn't see any quick way to anchor the #! to the beginning of a line. I'm leaving that up for anybody with better knowledge on those.

[bugarela]

I didn't touch Vim and Emacs here. I'm not very familiar with their grammars definition, but for both I didn't see any quick way to anchor the #! to the beginning of a line. I'm leaving that up for anybody with better knowledge on those.

Sure! I also don't really know how to do that, so I'll look it up some other time. VSCode is, by far, the most used one, so it's great that you fixed it there.