Change background of monaco editor

[enikonemeth]

Check the related issue: SenseNet/sensenet#893

[codecov]

Codecov Report

Merging #736 into develop will decrease coverage by 0.03%.
The diff coverage is n/a.

@@             Coverage Diff             @@
##           develop     #736      +/-   ##
===========================================
- Coverage    92.33%   92.30%   -0.04%     
===========================================
  Files          215      215              
  Lines         5809     5809              
  Branches      1468     1468              
===========================================
- Hits          5364     5362       -2     
- Misses         445      447       +2     

Impacted Files	Coverage Δ
...document-viewer-react/src/context/viewer-state.tsx	84.61% <0.00%> (-15.39%)	⬇️

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[sensenet]

Site name	Url	Last deploy
sn-app-dev	https://5f10188ac76c63fa9b3a631a--sn-app-dev.netlify.app	Thu Jul 16 2020 - 09:06:20 GMT+0000 (Coordinated Universal Time)
sn-react-component-docs-dev	https://5f1018846d51fc7f007f55a6--sn-react-component-docs-dev.netlify.app	Thu Jul 16 2020 - 09:06:14 GMT+0000 (Coordinated Universal Time)

[herflis]

🧁