Improve the tutorial table of contents accessibility

[jpaquim]

Is your feature request related to a problem? Please describe.
I feel a bit frustrated sometimes when trying o open another section of the tutorial in another tab, and invariably fail due to the table of contents being a <select>.

Describe the solution you'd like
It would be more intuitive and useful if it was possible to open a new section in a new tab from the right click menu, or by Cmd+clicking (so I guess just behaving like a regular <a> element).

How about replacing the single selection table of contents with a more accessible one with anchor elements?

Describe alternatives you've considered
It seems that this section is responsible for defining the DOM for this part of the page. https://github.com/sveltejs/svelte/blob/master/site/src/routes/tutorial/%5Bslug%5D/_TableOfContents.svelte#L80

I imagine that the solution would be along the lines of replacing it with the usual <nav>, <ol>, <li>, and <a> elements. Or maybe just add wrapper <a> elements in the TOC entries themselves.

How important is this feature to you?
It's a nice to have, but it doesn't really impact my daily work significantly.

I wouldn't mind tackling this issue, but I wanted to check if I was the only one slightly frustrated by this behavior.

[pushkine]

I remember I didn't find it great when I did it months ago
the workaround is to go to the page anyway then cmd click the history.back button instead

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[dummdidumm]

Closing as outdated, we have a new omnisite in a different repo now, and there's work planned to make it more navigateable