Add EngineArray Multi-Model [1/3]

[michaelfeil]

• This feature is a work in progress to introduce a new concept: EngineArray
• this enables usage of multiple engines at the same time / multi-mdoel deployment

Closes #13
#119

As a follow-up, need to make sure to launch multiple models via the CLI. This requires some refactoring of the cli. This is not part of this PR.

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 88.52459% with 7 lines in your changes are missing coverage. Please review.

Project coverage is 73.60%. Comparing base (59a13c0) to head (6abebe1).
Report is 4 commits behind head on main.

Files	Patch %	Lines
libs/infinity_emb/infinity_emb/engine.py	87.87%	4 Missing ⚠️
libs/infinity_emb/infinity_emb/infinity_server.py	86.36%	3 Missing ⚠️

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Additional details and impacted files

@@            Coverage Diff             @@
##             main     #200      +/-   ##
==========================================
+ Coverage   73.49%   73.60%   +0.11%     
==========================================
  Files          32       32              
  Lines        1811     1849      +38     
==========================================
+ Hits         1331     1361      +30     
- Misses        480      488       +8     

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