Use the VS Code FS API in RawFileSystem.

[ericsnowcurrently]

(for #8995)

This is the last part of un-reverting the FS changes.

• 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)
• [ ] The wiki is updated with any design decisions/details.

[codecov-io]

Codecov Report

Merging #9846 into master will increase coverage by <.01%.
The diff coverage is 98.63%.

@@            Coverage Diff             @@
##           master    #9846      +/-   ##
==========================================
+ Coverage   61.21%   61.22%   +<.01%     
==========================================
  Files         564      564              
  Lines       30152    30192      +40     
  Branches     4561     4567       +6     
==========================================
+ Hits        18458    18484      +26     
- Misses      10659    10675      +16     
+ Partials     1035     1033       -2

Impacted Files	Coverage Δ
src/client/common/platform/types.ts	100% <ø> (ø)	⬆️
src/client/common/platform/fs-temp.ts	100% <ø> (ø)	⬆️
src/client/common/platform/fileSystem.ts	80.97% <100%> (+3.75%)	⬆️
src/client/common/platform/errors.ts	98.36% <88.88%> (-1.64%)	⬇️
src/client/common/utils/platform.ts	70.58% <0%> (-5.89%)	⬇️
src/client/datascience/jupyter/jupyterNotebook.ts	4.38% <0%> (-0.18%)	⬇️
...ient/datascience/interactive-ipynb/nativeEditor.ts	56.86% <0%> (-0.13%)	⬇️
src/client/common/platform/fs-paths.ts	80.76% <0%> (+3.84%)	⬆️

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[sonarqubecloud]

Kudos, SonarCloud Quality Gate passed!

0 Bugs
0 Vulnerabilities (and 0 Security Hotspots to review)
0 Code Smells

No Coverage information
0.0% Duplication