Support for Custom Fonts in the App

[casperstorm]

As a user, I want the ability to use custom fonts in the app. I should be able to place font files in the config directory and specify them in the config file. The application should automatically detect new font files and utilize them instead of the default fonts.

Acceptance Criteria:

1. Have a designated font directory where font files can be placed.
2. The config file should have an option to specify the custom font files to be used.
3. Upon launching the app, it should detect and load the custom font files specified in the config file.
4. The app should handle any errors or missing font files gracefully, falling back to the default fonts if necessary.

[tarkah]

Cosmic-text supports using system fonts without needing to do anything in iced (no font::load needed). All we need from the user is font definitions where they specify the font family name.

I'll hit this next, it should be very easy to extend into our config