fix: compatibility with webpack@5

[alexander-akait]

This PR contains a:

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

Motivation / Use-Case

compatibility with latest webpack@5

Breaking Changes

No

Additional Info

webpack@5 has regression in invalidate method, so temporary comment some part of test (already written to sokra about this)

Also many test uses context: '/', it is invalid, context should be full path to directory.

This code:

// TODO Why? Need remove in future major release
              if (outputPath === '/') {
                outputPath = compiler.context;
              }

just workaround with invalid tests, i don't know why previously developer do this, maybe he did not understand or did not know how to write tests, this will remain a mystery to us

[alexander-akait]

As i written above we should rewrite tests in future

[codecov]

Codecov Report

Merging #473 into master will decrease coverage by 0.28%.
The diff coverage is 93.33%.

@@            Coverage Diff             @@
##           master     #473      +/-   ##
==========================================
- Coverage   97.37%   97.09%   -0.29%     
==========================================
  Files           7        7              
  Lines         305      310       +5     
  Branches      101      102       +1     
==========================================
+ Hits          297      301       +4     
- Misses          8        9       +1

Impacted Files	Coverage Δ
lib/fs.js	95.52% <93.33%> (-1.26%)	⬇️

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