Add command palette badge to new TopNavigation

[Twixes]

Changes

This adds a command palette badge to TopNavigation.tsx, which works much like the button in the old nav. Resolves #2645.

Also some tiny typing fixes.

[paolodamico]

I'm not 100% on board with this way of showing the command palette. Mainly because the badges at the top are meant as status badges, i.e. they do not pull attention on the regular course of business. Also, the gray doesn't really communicate that the element is clickable. In addition, this isn't particularly emphatic about the command palette.

The above being said, I'm not opposed to merging this for now.

[Twixes]

That seems like the best place for such a thing though IMO, akin to the macOS menu bar. Though definitely not prominent with this color. How about our primary blue?

I think the button we had in the old nav was ideal, with the keyboard shortcut shown, but that's harder to pull off in a way consistent with the new style.

[paolodamico]

I like it! Still think at some point in the near future we might come up with something different (particularly if we improve the search capabilities, we can consider changing to a search bar), but for now it's 👌👌, I've updated and merged master for cypress tests to pass.