fix: lint modules that are cached with webpack's filesystem cache

[facugaich]

This PR contains a:

• bugfix
• new feature
• code refactor
• test update
• typo fix
• metadata update

Motivation / Use-Case

If webpack is setup with cache type filesystem, the succeedModule hook is not called for cached modules and no linting is run for them. Tap the stillValidModule hook to lint cached modules.

Note regarding testing, I tried several strategies but the only one that I managed to get working was to create two different compilers and have the second one pickup the cache left by the first one.

Fixes #130

Breaking Changes

Additional Info

[linux-foundation-easycla]

The committers listed above are authorized under a signed CLA.

• ✅ login: facugaich / name: Facundo Gaich (cfb2ec8)

[alexander-akait]

/cc @ricardogobbosouza hello, can you review?

[codecov]

Codecov Report

Base: 100.00% // Head: 100.00% // No change to project coverage 👍

Coverage data is based on head (0cd8d4f) compared to base (ebce9be).
Patch coverage: 100.00% of modified lines in pull request are covered.

Additional details and impacted files

@@            Coverage Diff            @@
##            master      #197   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files            7         7           
  Lines          280       283    +3     
  Branches        78        78           
=========================================
+ Hits           280       283    +3     

Impacted Files	Coverage Δ
src/index.js	100.00% <100.00%> (ø)

Help us with your feedback. Take ten seconds to tell us how you rate us. Have a feature suggestion? Share it here.

☔ View full report at Codecov.
📢 Do you have feedback about the report comment? Let us know in this issue.

[instagibb]

Is this gonna be reviewed/merged anytime soon? Really keen to see this in a release

[ricardogobbosouza]

Sorry for the delay, my considerations:

1. The lint will run again on the cached files, impairs the performance.
2. The plugin should retrieve errors and warnings from cached files as @alexander-akait mentioned here ESLintPlugin not working consistently with cache.type = 'filesystem' #130 (comment)
3. I'm going to merge this PR because it solves this problem, but we need to deal with the performance

[facugaich]

@ricardogobbosouza Thank you!

Re: performance, could we use ESLint's own cache option for that? It seems like it would work for the non-threaded case at least, and you've mentioned that the threaded impl should be deprecated anyways in #143

[yoyo837]

This changes caused Hot Module Replacement build to be very slow after save files.