Tag and Category icons

[Seirade]

Is your feature request related to a problem? Please describe.
Since tags are used to convey many different kinds of information, it would be nice if it were possible to set their icons in order to break up the monotony.

Describe the solution you'd like
The Category editor should allow you to set an icon at the category-level. This will show you a menu that pops up and allows you to pick from Glyphs (font icons such as Open Iconic, Font Awesome, etc, that can be colored), Emoji (Twemoji?), or Custom. The Custom section would be where users can import their own icon and give it a name label.

When creating a Tag, its default icon should be set to null, and should it be null, it would inherit the Category icon (rather than copying the value, so that mass-editing would still be possible). However, Tags would also have a similar menu that lets you override the Category icon

Describe alternatives you've considered
N/A

Additional context
Below is just a basic idea for the menu's appearance. The Emoji section would be similar. The Custom section would have buttons that would allow you to Add/Edit/Delete icons from the menu. Add allows you to browse your computer for an icon to import. Edit would let you click on an icon to change the image used and/or the name label assigned. Delete would let you click on an icon to remove, perhaps with a confirmation dialog.

An alternate to text labels on the buttons could be icons such as ➕ 📝 🗑️