feat: add a noRuntime option

[cbazureau]

This PR contains a:

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

Motivation / Use-Case

As seen here webpack-contrib/css-loader#1362 and here #711 i've added a noRuntime option to avoid the runtime generation. Assets are still extracted and can be used for a custom loading methods.
Another PR (#807) tried to do something similar but does others things and will need a rebase. In comparaison i'm using a more minimal approach and add unit tests that shown that :

• link tags are not generated when noRuntime is true
• runtime is also not generated in this case

Breaking Changes

None

Additional Info

None

[linux-foundation-easycla]

The committers are authorized under a signed CLA.

• ✅ Cédric Bazureau (845b358)

[codecov]

Codecov Report

Merging #831 (3a68a3e) into master (e67af52) will increase coverage by 0.00%.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##           master     #831   +/-   ##
=======================================
  Coverage   92.80%   92.81%           
=======================================
  Files           6        6           
  Lines         723      724    +1     
  Branches      176      177    +1     
=======================================
+ Hits          671      672    +1     
  Misses         49       49           
  Partials        3        3           

Impacted Files	Coverage Δ
src/index.js	96.39% <100.00%> (+<0.01%)	⬆️

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[alexander-akait]

@cbazureau #832, just rename to runtime: boolean (default true)