refactor: Simplify API dashboard panel layout and tab management

[tangcent]

No description provided.

[github-actions]

📦 Plugin has been packaged for this PR. You can download easy-api-2.4.2.212.0.zip from the GitHub Actions workflow run by clicking on the "Artifacts" dropdown.

[codecov]

Codecov Report

❌ Patch coverage is 0% with 35 lines in your changes missing coverage. Please review.
✅ Project coverage is 53.879%. Comparing base (29838cf) to head (e8727bb).
⚠️ Report is 1 commits behind head on master.

Files with missing lines	Patch %	Lines
...ent/idea/plugin/api/dashboard/ApiDashboardPanel.kt	0.000%	35 Missing ⚠️

Additional details and impacted files

@@               Coverage Diff               @@
##              master      #613       +/-   ##
===============================================
- Coverage     53.908%   53.879%   -0.029%     
  Complexity      2366      2366               
===============================================
  Files            259       259               
  Lines          14699     14707        +8     
  Branches        3248      3254        +6     
===============================================
  Hits            7924      7924               
- Misses          5331      5339        +8     
  Partials        1444      1444               

Flag	Coverage Δ
unittests	53.879% <0.000%> (-0.029%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
...ent/idea/plugin/api/dashboard/ApiDashboardPanel.kt	0.000% <0.000%> (ø)

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