feat: use webpack inputFilesystem

[alexander-akait]

This PR contains a:

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

Motivation / Use-Case

Now we use webpack filesystem, so you can change it in runtime + now we cache fs calls, should be faster in watch mode

Breaking Changes

No

Additional Info

No

[codecov]

Codecov Report

Merging #531 into master will increase coverage by 0.09%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master     #531      +/-   ##
==========================================
+ Coverage   97.63%   97.72%   +0.09%     
==========================================
  Files           3        3              
  Lines         211      220       +9     
  Branches       66       73       +7     
==========================================
+ Hits          206      215       +9     
  Misses          5        5              

Impacted Files	Coverage Δ
src/index.js	98.05% <100.00%> (+0.08%)	⬆️

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