Full Site Editing: Add styling options to the Navigation Menu block

[Copons]

Currently, the Full Site Editing's Main Navigation block doesn't have any styling options (except the wide/full block width), and simply reuses the theme CSS .main-navigation class styles.

We should keep the theme CSS as default and fallback, but also let the user set their own styling options.

[noahtallen]

should we punt this in favor of core work?

[Copons]

should we punt this in favor of core work?

I'd love to add the same attributes as we are adding to the Site Title and Description.
Here colors are more annoying because menus are inherently more complicated, but it might be worth a try.

[apeatling]

@Copons I would only try this if it is one day of work, the colors work is almost already completed on the core navigation block from Ajax: WordPress/gutenberg#17832