feat(executors): list all available fetchers & executors in fetchers endpoint

[AndreyMarkinPPC]

No description provided.

[codecov-commenter]

Codecov Report

❌ Patch coverage is 25.00000% with 3 lines in your changes missing coverage. Please review.
✅ Project coverage is 90.64%. Comparing base (5ebb9d2) to head (c58e082).
⚠️ Report is 226 commits behind head on main.

Files with missing lines	Patch %	Lines
libs/executors/garf/executors/setup.py	25.00%	3 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #420      +/-   ##
==========================================
+ Coverage   88.23%   90.64%   +2.41%     
==========================================
  Files          61       82      +21     
  Lines        2600     4200    +1600     
==========================================
+ Hits         2294     3807    +1513     
- Misses        306      393      +87     

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