feat(sidebar service): add compact method

[yggg]

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:

[codecov]

Codecov Report

Merging #1997 into master will increase coverage by <.01%.
The diff coverage is 88.88%.

@@            Coverage Diff             @@
##           master    #1997      +/-   ##
==========================================
+ Coverage   84.06%   84.07%   +<.01%     
==========================================
  Files         235      235              
  Lines        7794     7803       +9     
  Branches      681      682       +1     
==========================================
+ Hits         6552     6560       +8     
  Misses       1042     1042              
- Partials      200      201       +1

Impacted Files	Coverage Δ
...mework/theme/components/sidebar/sidebar.service.ts	84% <100%> (+4%)	⬆️
...work/theme/components/sidebar/sidebar.component.ts	54.92% <75%> (+0.58%)	⬆️