Add support for break-out rooms

[SimonBrandner]

Implements matrix-org/matrix-spec-proposals#3985
Requires matrix-org/matrix-js-sdk#3753

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Done with a community 🎩 on as a part of my high-school graduation thesis

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 21.87500% with 25 lines in your changes missing coverage. Please review.

Project coverage is 24.94%. Comparing base (f529ae1) to head (b13bc63).
Report is 715 commits behind head on livekit.

Files	Patch %	Lines
src/button/Button.tsx	18.18%	18 Missing ⚠️
src/ClientContext.tsx	12.50%	7 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##           livekit    #1615      +/-   ##
===========================================
- Coverage    25.02%   24.94%   -0.08%     
===========================================
  Files           47       47              
  Lines         2382     2413      +31     
  Branches       434      437       +3     
===========================================
+ Hits           596      602       +6     
- Misses        1735     1760      +25     
  Partials        51       51              

Flag	Coverage Δ
unittests	24.94% <21.87%> (-0.08%)	⬇️

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