Compile CSS from Sass using Webpack

[podliashanyk]

Implemented changes:

• [x] Switched to building CSS from Sass with Webpack
• [x] Removed libsass as dependency
• [x] Updated docs
• [ ] Updated changelog

Closes #2871, and possibly #2719

Best reviewed commit-by-commit. Furthermore this PR could be split into several smaller PRs.

Further work:

• Fix deprecated syntax warnings and errors that webpack detected in Sass files (#2872)

Depends on #2855, #2859

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 0% with 1 lines in your changes are missing coverage. Please review.

Project coverage is 56.69%. Comparing base (9cfd877) to head (f36092e). Report is 12 commits behind head on master.

Files	Patch %	Lines
python/nav/startstop.py	0.00%	1 Missing :warning:

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #2849   +/-   ##
=======================================
  Coverage   56.69%   56.69%           
=======================================
  Files         602      602           
  Lines       43971    43971           
=======================================
  Hits        24931    24931           
  Misses      19040    19040           

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[github-actions[bot]]

Test results

     12 files       12 suites   11m 31s :stopwatch: 3 320 tests 3 320 :heavy_check_mark: 0 :zzz: 0 :x: 9 435 runs  9 435 :heavy_check_mark: 0 :zzz: 0 :x:

Results for commit f36092e3.

:recycle: This comment has been updated with latest results.

[sonarqubecloud[bot]]

Quality Gate passed

Issues
3 New issues
0 Accepted issues

Measures
0 Security Hotspots
No data about Coverage
0.0% Duplication on New Code

See analysis details on SonarCloud

[hmpf]

This is a continuation of #2859? I'd rather not review this one until that one is merged and this one updated accordingly.

[podliashanyk]

This is a continuation of #2859? I'd rather not review this one until that one is merged and this one updated accordingly.

Thats right, this one is blocked by #2859. There will be a new rebase when #2859 is merged 😌