Dropdown menus in navbar

[yrjarv]

Problem
It seems to me like WCAG 2.4.5 is not currently met, as you can only navigate to some pages by clicking through several other pages. It is also inconvenient to have to wait for several pages to load before you can get to your destination.

Solution
Remaking the navigation on AppBar so that it reflects the site structure. This would of course need quite a lot of work so that pages you are not authorized to see show up, so perhaps this should wait to after the API rework?

Such a change would also require changes in Sanity: We either need more buttons to be added in the CMS, or we could drop the CMS completely and base the buttons solely off of file structure. The latter would handle newly added pages more easily, but probably has some drawbacks too.