feat: resolve issue #1028: optimising naming for best compression

[denisx]

This PR contains a:

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

Motivation / Use-Case

resolve issue #1028

For efficient gzip/br compression, plugin combine css hash via one symbol name,
as a classname position at file, with filepath hash:base64:8, to have strong sequences.

[denisx]

have some bugs from master :/
npm audit fix change package-lock.json ...

[joseprio]

We use a similar technique, but just defining a custom getLocalIdent. However, I don't think this plays well with the caching mechanism, as the classname generation isn't stable, right?

[denisx]

@joseprio

However, I don't think this plays well with the caching mechanism, as the classname generation isn't stable, right?

Css-loader get async files and parse, it is allways randomized work. Class save classnames positions for every file (a,b,c,...). As a file-path, it is always stable content hash for project. It is cache frendly.

[codecov]

Codecov Report

Merging #1062 into master will decrease coverage by 0.31%.
The diff coverage is 93.65%.

@@            Coverage Diff             @@
##           master    #1062      +/-   ##
==========================================
- Coverage   97.17%   96.86%   -0.32%     
==========================================
  Files          10       11       +1     
  Lines         460      542      +82     
  Branches      153      176      +23     
==========================================
+ Hits          447      525      +78     
- Misses         12       16       +4     
  Partials        1        1              

Impacted Files	Coverage Δ
src/plugins/one-letter-css.js	93.65% <93.65%> (ø)
src/index.js	100.00% <0.00%> (ø)
src/utils.js	98.88% <0.00%> (+0.11%)	⬆️

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[denisx]

and https://gist.github.com/denisx/9dc0e8c542b810e67f41691c89e7b948 for check hash length

[jsf-clabot]

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1 out of 2 committers have signed the CLA.

✅ denisx
❌ Denis 🎃 Khripkov

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[denisx]

Add css hash len suggest - we have full hash map after css-1-letter running.