ToC View mode

[konzz]

Implement the visualisation of the table of contents tab.

This includes:

• Loading the ToC
• Navigating within the document using the ToC
• 'Mark as reviewed' button
• Add an "blank" view similar to the Search tab or References Tab examples

We do not currently have an edit view (drag and drop, edit labels, delete entries, add new ones...), so that functionality is out of scope for this issue.
Designs