Fix load_module bug with unserializable objects

[dagardner-nv]

Description

• PR Update cast_from_pyobject to throw on unsupported types rather than returning null #451 changed the cast_from_pyobject behavior to throw an exception rather than returning a null.
• This broke dfp_integrated_training_batch_pipeline.py which stored datetime objects in the module config.
• This PR back-patches the unserializable_handler_fn functionality from 24.06, and adds a handler to ModuleRegistryProxy::get_module_constructor and BuilderProxy::load_module_from_registry to restore the original functionality as a quick-fix for 24.03

Checklist

• I am familiar with the Contributing Guidelines.
• New or existing tests cover these changes.
• The documentation is up to date with these changes.

[cwharris]

LGTM

[codecov]

Codecov Report

Merging #462 (0c1a001) into branch-24.03 (bd7955e) will increase coverage by 0.00%.
Report is 1 commits behind head on branch-24.03.
The diff coverage is 88.23%.

Additional details and impacted files

@@              Coverage Diff              @@
##           branch-24.03     #462   +/-   ##
=============================================
  Coverage         73.68%   73.68%           
=============================================
  Files               400      400           
  Lines             14275    14286   +11     
  Branches           1113     1115    +2     
=============================================
+ Hits              10518    10527    +9     
- Misses             3757     3759    +2     

Flag	Coverage Δ
cpp	70.18% <35.29%> (-0.05%)	⬇️
py	41.82% <86.66%> (+0.07%)	⬆️

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Files	Coverage Δ
python/mrc/_pymrc/src/utils.cpp	86.36% <100.00%> (+0.82%)	⬆️
python/mrc/_pymrc/src/module_registry.cpp	86.48% <75.00%> (-1.75%)	⬇️
python/mrc/_pymrc/src/segment.cpp	81.81% <75.00%> (-0.31%)	⬇️

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[dagardner-nv]

Closing this PR in favor of fixing the issue on the Morpheus side, serializing to a json null simply hid a bug in Morpheus.