Visualization infrastructure cleanup

[timroes]

This issue outlines a couple of cleanups we still wanted/should do within the visualization infrastructure:

• [ ] Potentially combine the visualize and visualizations plugin into one. The split was mainly done because of codeownership of those plugins. Now since the same team owns them there is no really a use-case to keep those (anyway arbitrary drawn boundary) still alive and we should bring them back into one plugin. There could also be a use-case in case of dependencies to not keep the visualize application in the same, so we still need to make a final decicion about this. @sulemanof and @timroes discussed this, and we agreed to keep them separate, given the dependencies.
• After we've created individual renderers for all visualizations (see Renderers for all visualizations #46801) we should cleanup the whole (then unused) Visualization class and a couple of dependant classes (like Vis).
• Also after that, we should remove the build_pipelines.ts utility.
• TypeScript cleanups:
  • Remove any index signature from VisType (src/plugins/visualizations/public/vis_types/types_service.ts)

cc @stratoula

[elasticmachine]

Pinging @elastic/kibana-app (Team:KibanaApp)