Remove/merge preferred controller, default controller, loader, registration, etc

[rebornix]

Currently we have both controllerDefaultService and controllerPreferredService, which have overlap but differ a bit at the same time.

[rebornix]

While we consolidate these two services, we should probably also simply how we create default/preferred controller, which currently is based on some heuristics, including:

• whether it's localOnly
• whether there is any kernel created (when there is an active python intepreter)
• whether we are connected to a remote (traditional flow)

[DonJayamanne]

• ControllerDefaultService -> Determines the 'default' kernel for a notebook. Default is what kernel should be used if there's no metadata in a notebook.
• ControllerPreferredService -> Computes and tracks the preferred kernel for a notebook. Preferred is determined from the metadata in the notebook. If no metadata is found, the default kernel is used.
• KernelRankingHelper.isExactMatch -> This seems to doe both of the above items as well!
• IW - We create the controller for active interrpeter always
• CibtrikkerKiader - we create active interpreter controller
• notebookKernelSourceTracker - we show/hide controllers per notebook
• controllerPreferredService, vscodeNotebookController and notebookKernelSourceTracker
  • All three of these update the affinity of a controller with a notebook
• Also found that the methdo findPreferredKernelExactMatch doesn't find the exact match, instead this finds a close match.
• Stop using preferred and defaujlt service, this is only used in old code paths and IW and IW debugger &oh yes tests.

[DonJayamanne]

Next to do item,

• KernelRankingHelper.isExactMatch -> This seems to doe both of the above items as well!

[DonJayamanne]

Most of the work is done, we'll need to wait for the new Kernel Picker to be stable, and once we delete the old code, then reviewing the existing code/structure would be simpler

[DonJayamanne]

Marking as closed