feat: support SASS-PATH env variable

[alexander-akait]

This PR contains a:

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

Motivation / Use-Case

support resolution from SASS_PATH

Breaking Changes

In theory can be in some rare cases

Additional Info

No

[codecov]

Codecov Report

Merging #836 into master will increase coverage by 0.03%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master     #836      +/-   ##
==========================================
+ Coverage   97.81%   97.84%   +0.03%     
==========================================
  Files          10       10              
  Lines         183      186       +3     
  Branches       61       63       +2     
==========================================
+ Hits          179      182       +3     
  Misses          4        4              

Impacted Files	Coverage Δ
src/getSassOptions.js	100.00% <100.00%> (ø)

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