Dokka v2: show all known subtypes

[DanySK]

Is your feature request related to a problem? Please describe

I have a system whose components are created based on the types requested by the user.
It is very handy to find in the documentation the list of all inheritors of some interface across all modules.

This feature is present in Javadoc:

Describe the solution you'd like

In non-final members, list all known subtypes, possibly in a tab similar to the "Members" one:

Describe alternatives you've considered

Alternatively, there might be dedicated search options.