feat: add custom css class on overlays

[FourthOf5]

Please read and mark the following check list before creating a pull request:

• I read and followed the CONTRIBUTING.md guide.
• I read and followed the New Feature Checklist guide.

Short description of what this resolves:

Closes #1148

[codecov]

Codecov Report

Merging #2067 into master will increase coverage by 0.48%.
The diff coverage is 88.88%.

@@            Coverage Diff             @@
##           master    #2067      +/-   ##
==========================================
+ Coverage   84.08%   84.57%   +0.48%     
==========================================
  Files         235      235              
  Lines        8031     8038       +7     
  Branches      705      706       +1     
==========================================
+ Hits         6753     6798      +45     
+ Misses       1068     1020      -48     
- Partials      210      220      +10

Impacted Files	Coverage Δ
...ramework/theme/components/dialog/dialog.service.ts	89.23% <ø> (ø)	⬆️
...framework/theme/components/dialog/dialog-config.ts	100% <100%> (ø)	⬆️
.../components/context-menu/context-menu.directive.ts	90.19% <100%> (+0.19%)	⬆️
...framework/theme/components/toastr/toastr-config.ts	84.61% <100%> (+0.61%)	⬆️
...amework/theme/components/toastr/toast.component.ts	79.16% <83.33%> (+33.71%)	⬆️
...k/theme/components/cdk/overlay/overlay-position.ts	95.68% <0%> (+1.72%)	⬆️
...ramework/theme/components/toastr/toastr.service.ts	97.5% <0%> (+7.5%)	⬆️
...rk/theme/components/cdk/overlay/position-helper.ts	47.54% <0%> (+11.47%)	⬆️
...me/components/toastr/toastr-container.component.ts	88.88% <0%> (+22.22%)	⬆️

[yggg]

👍