Use new VS Code filesystem API.

[ericsnowcurrently]

(for #6911)

This PR builds on #7915, focusing only on the move to the new filesystem API. Note that there are 6 functions (in addition to glob() and tmp.file()) that I was not able to convert due to a lack of functionality in the new API. I have opened upstream issues to address that.

• 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 #8307 into master will increase coverage by 0.58%.
The diff coverage is 85.89%.

@@            Coverage Diff             @@
##           master    #8307      +/-   ##
==========================================
+ Coverage   58.07%   58.66%   +0.58%     
==========================================
  Files         526      526              
  Lines       26827    27168     +341     
  Branches     4040     4043       +3     
==========================================
+ Hits        15581    15938     +357     
+ Misses      10389    10368      -21     
- Partials      857      862       +5

Impacted Files	Coverage Δ
src/client/common/platform/types.ts	100% <ø> (ø)	⬆️
src/client/workspaceSymbols/provider.ts	93.33% <100%> (ø)	⬆️
src/client/common/platform/fileSystem.ts	74.77% <85.71%> (-2.22%)	⬇️
...lient/datascience/jupyter/jupyterSelfCertsError.ts	100% <0%> (ø)	⬆️
src/client/debugger/extension/serviceRegistry.ts	100% <0%> (ø)	⬆️
src/client/common/variables/serviceRegistry.ts	100% <0%> (ø)	⬆️
src/client/common/process/serviceRegistry.ts	100% <0%> (ø)	⬆️
src/client/common/dotnet/serviceRegistry.ts	100% <0%> (ø)	⬆️
src/client/linters/serviceRegistry.ts	100% <0%> (ø)	⬆️
... and 30 more

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[kimadeline]

The link you provided says "commit range not found", so I've been using 6f63744 (Fix the tmp FS tests. which is the last commit in #7915) as my baseline: https://github.com/microsoft/vscode-python/pull/8307/files/6f6374441e74d62111008a3dfef0961c9bd43e40..HEAD, and it's not just 6 files changed and 932 insertions:

[ericsnowcurrently]

FYI, the one lingering failure (functional tests) is something I have not been able to reproduce locally yet.

[DonJayamanne]

Not sure whether this is still ready for review.
It would be better to split such PRs into smaller chunks, or perhaps we've stopped doing that.
E.g. we could implement the new API in one PR & not use it anywhere, then update other files in another PR, then more i.e. gradually strip out the use of the old API in increments... making it much easier to test and review.
Also, I think it would be easier to get the work done as well, i.e. split amongst others.. Anyways, just a suggestion.
@karthiknadig /cc

[DonJayamanne]

I believe all of my original concerns have been addressed.
I don't wish to hold the PR unnecessarily. hence approving.

[ericsnowcurrently]

Oh, I absolutely agree about smaller PRs. This one was an aberration due to lack of clarity early on back when the PR was much smaller. :)