feat: collapse sensitive channel notes

[anatawa12]

What

Closer #16999

にりみすで使用しているものを少し改造してPRにしました

Why

Additional info (optional)

Checklist

• Read the contribution guide
• Test working in a local environment
• (If needed) Add story of storybook
• (If needed) Update CHANGELOG.md
• (If possible) Add tests

[codecov]

Codecov Report

❌ Patch coverage is 0% with 13 lines in your changes missing coverage. Please review.
✅ Project coverage is 13.94%. Comparing base (d35ddc7) to head (57e3fba).
⚠️ Report is 12 commits behind head on develop.

Files with missing lines	Patch %	Lines
packages/frontend/src/components/MkNote.vue	0.00%	8 Missing and 4 partials ⚠️
packages/frontend/src/pages/timeline.vue	0.00%	1 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##           develop   #17001       +/-   ##
============================================
- Coverage    62.83%   13.94%   -48.89%     
============================================
  Files         1150      237      -913     
  Lines       115242    11293   -103949     
  Branches      7896     3738     -4158     
============================================
- Hits         72409     1575    -70834     
+ Misses       40690     7592    -33098     
+ Partials      2143     2126       -17     

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[kakkokari-gtyih]

extension