Improve performance of the Table of Contents

[soywiz]

Is your feature request related to a problem? Please describe

In my libraries https://dokka.korge.org/ table of contents is laggy which is a bit frustrating. And in some cases a pretty much unusable.
#2695 (comment)
Also maybe it displays too much information. I might only want classes and packages to reduce it.

Describe the solution you'd like

• Support limiting the ToC to packages and classes
• Building the ToC HTML DOM nodes on demand
• Use HTML history API to make local navigations to not reload the ToC but update only the current node and the changed main content

Described in detail here: #2695 (comment)

[ZacSweers]

Big +1 on this. The performance issues with dokka make it more or less unusable for nontrivial projects. Using firefox/safari helps, but still suffers to a lesser extent.