Tidy up post-refactoring analysis modules

[IgnatBeresnev]

The refactoring done in #3034 uncovered a lot of difficult to comprehend code, as well as introduced more code / abstractions that are in themselves difficult to comprehend. The PR was merged into master prematurely to avoid having an enormous long-lived branch just collecting merge conflicts, so it's not perfect to say the least, and some of the code needs to be revisited in the near future while the context is still fresh in memory.

This is an umbrella issue for post-refactoring refactorings.

Issues:

• Move analysis-related unit tests from dokka-base into the new analysis modules. Note: some tests rely on the implementation details, so some refactoring is needed as well. Assignee: @IgnatBeresnev
• Add detailed descriptions for the new analysis modules. Update developer guides.
• Add an internal switch between implementations (K1 and K2) of the Analysis API
• Tidy up the Java Analysis module:
  • Remove excessive abstractions that were needed at the time of refactoring, but are not needed now.
  • Document the general flow and internals of the Java analysis, especially when it comes to how the @inheritdoc tag works.
  • Resolve numerous fresh TODO comments, marked as TODO [beresnev]
• Remove the dependency on jsoup in analysis-markdown-jb (used for something insignificant)
• Remove the dependency on analysis-markdown-jb in analysis-java-psi (used for something insignificant)
• Resolve numerous fresh TODO comments in dokka-base and other modules. The TODOs are marked as TODO [beresnev]