Add support for `typeHierarchy/supertypes` and `typeHierarchy/subtypes` and integrate those via the `codeInsight.gotoSuper` and `codeInsight.lineMarkerProvider` EPs.

JetBrains' IDEs provide extensive support for navigating up and down type hierarchy relationships. Some of this is already integrated via LSP4IJ, e.g., Go To Implementation(s) via #636, but others are missing. Minimally support for typeHierarchy/supertypes should be added and integrated into the IDE via the codeInsight.gotoSuper EP. I'm not sure whether or not typeHierarchy/subtypes would add much vs. what is already used for Go To Implementation(s).

Additionally it would be nice to add support for type/method hierarchy relationships in the editor gutter area via codeInsight.lineMarkerProvider and the information from these LSP features to provide clear visual representations of these type inheritance relationships.

Start by reviewing the existing Go To Implementation(s) integration referenced in #636, then compare it with the LSP typeHierarchy/supertypes and typeHierarchy/subtypes specifications. Trace how the codeInsight.gotoSuper and codeInsight.lineMarkerProvider extension points are integrated; done requires an agreed scope and working type-hierarchy navigation or gutter representations.