Canvas: Emoji picker and layout fixes

✨ Minor updates

Canvas now features an emoji picker to allow easier insertion of emojis in the main documents as well as in notes. Type ":" followed by a single character to trigger it.

🐛 Notable bugfixes

Text in numbered lists no longer incorrectly render with tabular alternates

Print style sheets should now correctly display content beyond the first page

Attempting to load a page with an invalid comment ID will still display the comments panel and warn the user

Improves document layout on smaller breakpoints