use posix path as assets key

[snadn]

This PR contains a:

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

Motivation / Use-Case

should use posix path as assets key that consistent with webpack

Breaking Changes

Additional Info

[alexander-akait]

Why? What is problem?

[snadn]

1. Consistent with webpack
   

2. Consistent with copy-webpack-plugin@4

3. Consistent with option and can be used by other plugin friendly
   

[alexander-akait]

Don't use / in to, it is not compatobility with windows, use path.join/path.resolve

[snadn]

I think the key of assets should be treated as path of url instead of path of filesystem.

Regarding the third point, the value of 'to' may be 'js' (a dir), And my configuration in ‘tags’ is still expected to be ‘js/xxx.js’

And the first and second points are also important reasons, especially the first point.

[alexander-akait]

@snadn no, linux support \ as part of name so in theory it can break cache

[snadn]

@evilebottnawi But this is just that this pr modification is not good enough, but using ‘/’ is still more reasonable. Maybe getting posix path and record it when getting the file path will be better.

ps: just change the key of assets will break cache? Whether it is in window or linux, the keys obtained are the same.The potential problem should be that multiple files may be mapped to a key

[alexander-akait]

@snadn

1. Use normalize-path instead posix
2. Need tests

[codecov]

Codecov Report

Merging #378 into master will decrease coverage by 0.28%.
The diff coverage is 83.33%.

@@            Coverage Diff             @@
##           master     #378      +/-   ##
==========================================
- Coverage   94.82%   94.53%   -0.29%     
==========================================
  Files           9        9              
  Lines         290      293       +3     
  Branches       78       81       +3     
==========================================
+ Hits          275      277       +2     
- Misses         14       15       +1     
  Partials        1        1

Impacted Files	Coverage Δ
src/postProcessPattern.js	88.75% <83.33%> (-0.87%)	⬇️

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[snadn]

@evilebottnawi Can this pr be merged?

[alexander-akait]

Looks like related #383

[jeffposnick]

I was going to file a PR (see https://github.com/webpack-contrib/copy-webpack-plugin/compare/master...jeffposnick:windows-fix?expand=1) but I see that this PR should address it just as well.