WIP: collect and assert which links are really missing in kotlinx projects

[whyoleg]

This is just an exploration that collects unresolved links in one place and shows which links Dokka generates in kotlinx projects.

Reasons:

• Dokka should not generate links (and warn about it) to classes excluded from rendered documentation #4448
  • skipped deprecated declarations via skipDeprecated = true
  • internal declarations in annotations
• Links to constructor parameters are unresolved #4328
  • constructor parameters (links ending in --root--.html)
• Include protected non-final members of public classes by default #4201
  • documentedVisibilities includes only Public by default
  • links to protected declarations, like to JsonTransformingSerializer.transformDeserialize