Add some tests for bar

[sarahd93]

Checklist:

• Tests
• CHANGELOG Entry

[codecov]

Codecov Report

Merging #1328 into gsa-8.0 will increase coverage by 0.3%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           gsa-8.0    #1328     +/-   ##
==========================================
+ Coverage    34.43%   34.74%   +0.3%     
==========================================
  Files          959      959             
  Lines        21595    21597      +2     
  Branches      5977     5978      +1     
==========================================
+ Hits          7437     7503     +66     
+ Misses       12803    12753     -50     
+ Partials      1355     1341     -14

Impacted Files	Coverage Δ
gsa/src/web/components/bar/progressbar.js	100% <100%> (+30.43%)	⬆️
gsa/src/web/utils/severity.js	72.97% <0%> (+21.62%)	⬆️
gsa/src/web/components/bar/statusbar.js	87.17% <0%> (+25.64%)	⬆️
gsa/src/web/components/bar/titlebar.js	77.27% <0%> (+40.9%)	⬆️
gsa/src/web/components/bar/toolbar.js	100% <0%> (+50%)	⬆️
...sa/src/web/components/provider/iconsizeprovider.js	88.88% <0%> (+66.66%)	⬆️
gsa/src/web/components/bar/severitybar.js	89.47% <0%> (+78.94%)	⬆️

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[bjoernricks]

Looks good. Only the changelog entry should be updated and some additional tests could be added.