add monarch app def to use monarchs torchrun

[colin2328]

Summary:
RFC diff to use monarch's torchrun runner .

creates an app def that

Differential Revision: D86155019

[meta-codesync]

@colin2328 has exported this pull request. If you are a Meta employee, you can view the originating Diff in D86155019.

[codecov-commenter]

Codecov Report

❌ Patch coverage is 4.54545% with 21 lines in your changes missing coverage. Please review.
✅ Project coverage is 91.34%. Comparing base (dd683f4) to head (ce80778).

Files with missing lines	Patch %	Lines
torchx/components/dist.py	4.54%	21 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1160      +/-   ##
==========================================
- Coverage   91.63%   91.34%   -0.29%     
==========================================
  Files          84       84              
  Lines        6595     6617      +22     
==========================================
+ Hits         6043     6044       +1     
- Misses        552      573      +21     

Flag	Coverage Δ
unittests	91.34% <4.54%> (-0.29%)	⬇️

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