feat: Implement EnsembleTrigger

[robinholzi]

Motivation

As we have had the EnsebleTriggerConfig for quite some time, I have already fully integrated it.

Note:

Support for the new (unmerged) trigger policies PerformanceTrigger and CostTrigger must still be added.

[codecov]

Codecov Report

Attention: Patch coverage is 95.09804% with 5 lines in your changes missing coverage. Please review.

Project coverage is 85.25%. Comparing base (6faf871) to head (71fb4ff).
Report is 2 commits behind head on main.

Files	Patch %	Lines
...yn/supervisor/internal/triggers/ensembletrigger.py	94.25%	5 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #597      +/-   ##
==========================================
+ Coverage   85.14%   85.25%   +0.10%     
==========================================
  Files         246      247       +1     
  Lines       10886    10979      +93     
==========================================
+ Hits         9269     9360      +91     
- Misses       1617     1619       +2     

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[github-actions]

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[MaxiBoether]

Thank you. I had a few small comments. I didn't realize this needs some caching logic because in mind I only had en ensemble that triggers if any subtrigger triggers but yeah with an arbitrary strategy such as min n we need this sophisticated logic indeed.