multiplexingDebugService for the web

[sadasant]

Migrated the multiplexingDebugService to the web, for #9665

This PR gets us closer to the meatier section of the migration of the variable views. The highlight in this case is making the IJupyterDebugService optional in the multiplexingDebugService.

Feedback appreciated!

[rchiodo]

I think you could instead rename multiplexingDebugService.node.ts to multiplexingDebugService.ts and just have the node specific parts optional.

[sadasant]

@rchiodo can do! thank you for the feedback 👍

[codecov-commenter]

Codecov Report

Merging #10070 (1e93d5d) into main (e6f523d) will decrease coverage by 0%.
The diff coverage is 28%.

@@          Coverage Diff           @@
##            main   #10070   +/-   ##
======================================
- Coverage     64%      64%   -1%     
======================================
  Files        216      215    -1     
  Lines      10060    10047   -13     
  Branches    1613     1619    +6     
======================================
- Hits        6508     6456   -52     
- Misses      3028     3064   +36     
- Partials     524      527    +3     

Impacted Files	Coverage Δ
src/platform/debugger/multiplexingDebugService.ts	47% <28%> (ø)
src/platform/export/exportUtil.node.ts	73% <0%> (-13%)	⬇️
src/platform/common/process/proc.node.ts	77% <0%> (-3%)	⬇️
...c/platform/common/process/pythonDaemonPool.node.ts	74% <0%> (-2%)	⬇️
src/platform/common/process/baseDaemon.node.ts	49% <0%> (-2%)	⬇️
src/platform/errors/errorHandler.ts	62% <0%> (-1%)	⬇️
src/platform/common/types.ts	100% <0%> (ø)
src/platform/export/types.ts	100% <0%> (ø)
src/platform/logging/types.ts	100% <0%> (ø)
src/platform/common/platform/types.ts	100% <0%> (ø)
... and 35 more

[rchiodo]

Looks good, just some minor fixups.

[sadasant]

@IanMatthewHuff @rchiodo thank you so much for your kind and thoughtful reviews! I will polish this up on Monday. 🙏 thanks again!