feat: add svgo implementation

[RAX7]

This PR contains a:

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

Motivation / Use-Case

The imagemin lib is unmaintained for a year. This means that svgo will never be updated to the latest version. So I created an implementation independent of imagemin for svgo.
It's also useful for users using imagemin just to minify only svg files.

Additional Info

I have edited tsconfig to avoid svgo bug svg/svgo#1700
Now it has "skipLibCheck": true

[codecov]

Codecov Report

Base: 75.69% // Head: 76.32% // Increases project coverage by +0.63% 🎉

Coverage data is based on head (f95b41a) compared to base (dc0a67a).
Patch coverage: 100.00% of modified lines in pull request are covered.

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #369      +/-   ##
==========================================
+ Coverage   75.69%   76.32%   +0.63%     
==========================================
  Files           4        4              
  Lines         683      697      +14     
  Branches      265      268       +3     
==========================================
+ Hits          517      532      +15     
+ Misses        137      136       -1     
  Partials       29       29              

Impacted Files	Coverage Δ
src/index.js	95.62% <100.00%> (+0.02%)	⬆️
src/utils.js	59.78% <100.00%> (+1.43%)	⬆️
src/loader.js	97.08% <0.00%> (+0.97%)	⬆️

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[alexander-akait]

@RAX7 Thank you.

If you intrested to improve perf in this plugin, we can implement multithreading here (I think it will improve perf very well), in other minimizer plugins (terser/css/etc) we implemented it using jest-worker, so we can just move this solution here (under the option) and improve perf, just idea

[RAX7]

@alexander-akait You are welcome!
I'll take a look at jest-worker and try to use it later.