Dev server: Don't focus nav on page load

[bennypowers]

Not sure if this is really a blocking issue. But when you click on a component demo from the nav, a new page loads, and focus returns to the top of the nav on the first nav item, not the top of the page itself. I feel like this is most likely an accessibility error. After page load I would assume focus is on the document, usually followed by a skip-nav link which could skip the header links (logo/github) and then place focus on the main navigation. If the main nav is hidden skip nav might have to then place focus on the hamburger menu button (noted this isn't a saved preference so this might be moot). This gives the user the option to click a header link after page load. There is also a visual style applied with :focus-visible which almost makes it look like an active page indicator.

Otherwise LGTM

Originally posted by @zeroedin in #2072 (comment)

[zeroedin]

This issue was resolved previously in an unlinked PR.

The second part of this issue was the lack of skip-nav link which is being resolved separately in: #2550