Refactor kernel code into a 'kernels' folder

[rchiodo]

Fixes #8970

Move all kernel related code (okay maybe not all but a lot) into a 'kernels' subfolder and organize according to raw/jupyter/common

• Pull request represents a single change (i.e. not fixing disparate/unrelated things in a single PR).
• Title summarizes what is changing.
• Has a news entry file (remember to thank yourself!).
• Appropriate comments and documentation strings in the code.
• Has sufficient logging.
• Has telemetry for enhancements.
• Unit tests & system/integration tests are added/updated.
• Test plan is updated as appropriate.
• package-lock.json has been regenerated by running npm install (if dependencies have changed).

[rchiodo]

I should probably fix these.

[DonJayamanne]

Yeah, rxjs is a large package, and slow to load.

[codecov-commenter]

Codecov Report

Merging #9313 (68b7d5f) into main (fb383f3) will increase coverage by 0%.
The diff coverage is 100%.

❗ Current head 68b7d5f differs from pull request most recent head f53990a. Consider uploading reports for the commit f53990a to get more accurate results

@@           Coverage Diff           @@
##            main   #9313     +/-   ##
=======================================
  Coverage     72%     72%             
=======================================
  Files        377     298     -79     
  Lines      24706   16845   -7861     
  Branches    3998    2568   -1430     
=======================================
- Hits       17793   12146   -5647     
+ Misses      5300    3734   -1566     
+ Partials    1613     965    -648     

Impacted Files	Coverage Δ
src/client/common/errors/types.ts	70% <ø> (+3%)	⬆️
src/client/datascience/data-viewing/dataViewer.ts	59% <ø> (ø)
...cience/data-viewing/jupyterVariableDataProvider.ts	68% <ø> (ø)
...data-viewing/jupyterVariableDataProviderFactory.ts	100% <ø> (ø)
src/client/datascience/data-viewing/types.ts	100% <ø> (ø)
...datascience/editor-integration/cellhashprovider.ts	76% <ø> (ø)
...science/errors/jupyterDebuggerNotInstalledError.ts	57% <ø> (ø)
...e/errors/jupyterDebuggerRemoteNotSupportedError.ts	66% <ø> (ø)
...ient/datascience/errors/jupyterWaitForIdleError.ts	100% <ø> (ø)
src/client/datascience/errors/kernelDiedError.ts	100% <ø> (ø)
... and 165 more