Admin UI: restructured sidebar to made dev actions more noticeable

[Vultraz]

Resolves #1190 based on @jesstelford 's mockup. Open to suggestions as to the design, but I think it looks pretty good!

[changeset-bot]

🦋 Changeset is good to go

Latest commit: 0ba50d9

We got this.

This PR includes changesets to release 2 packages

Name	Type
@arch-ui/navbar	Patch
@keystonejs/app-admin-ui	Minor

Not sure what this means? Click here to learn what changesets are.

Click here if you're a maintainer who wants to add another changeset to this PR

[Vultraz]

I wonder if it would look better without the icons... 🤔 Thoughts?

[lucatk]

Quick question (also, the redesign looks really good I think!):
Currently, the sidebar does not have any background color, resulting in overlapping elements when List content ends up being wider than my browser window.

A quick fix would be adding a background color to the sidebar. I determined it would belong here:

<PrimaryNav
    onMouseEnter={handleMouseEnter}
    onMouseLeave={handleMouseLeave}
-   style={makeResizeStyles('width')}
+   style={{
+       ...makeResizeStyles('width'),
+       backgroundColor: colors.page,
+   }}
 >

I haven't worked out how to contribute with all the monorepo stuff and this being just a single line of code deemed it too much work to figure it out right now. Therefore, this PR seemed like a good place for that change (if the PR is going to be merged any time soon, otherwise a hotfix would be appreciated)

[timleslie]

@Vultraz Are you able to follow up on the suggestion from @lucatk ? Let me know, I'll hold off merging this until you get back to me just so we don't lose the info.

[Vultraz]

@timleslie done 👍

[Vultraz]

How come Netlify is on the fritz today? 🤔