Ensure the hide_toc theme option behaves as expected

[stevejpurves]

Since #444 this may not longer be the case as we not also have nav components in the sidebar.
For any changes consider not drilling hide_toc down into components and how they might map to mobileOnly & hideToc props.

Desired behaviour hide_toc is that the table of contents should never be shown.

todo

• let's map out the user stories for end states

[agoose77]

Adding to this (Steve and I were in a Zoom meeting), right now it feels like we have a lot of confusing state options internally. We identified that there are really three behaviours that we want to capture:

1. Users have a ToC, and maybe have a nav. They want the primary sidebar to be visible at all times (either as a drawer, or fixed on the page). They want the burger menu to appear only when the sidebar behaves as a drawer.
2. Users don't have a ToC, and have a nav. They want to hide_toc so that the primary sidebar is not visible unless the primary nav needs to be folded into the sidebar. They want the burger menu to appear when the sidebar is visible and acting as a drawer.
3. Users don't have a ToC or a nav. They never want to see the primary sidebar or burger menu.

To me, that means hide_toc is the only configurable theme option. The rest is just reactive semantics.

Steve reminded me that we need to think about how to achieve this with SSR and hydration.