Add JSONValues container for holding Python values as JSON objects if possible, and as pybind11::object otherwise

[dagardner-nv]

Description

• Add an optional unserializable_handler_fn callback to mrc::pymrc::cast_from_pyobject which will be invoked for any unsupported Python object. Allowing for serializing unsupported object.
  ex:

    pymrc::unserializable_handler_fn_t handler_fn = [](const py::object& source,
                                                       const std::string& path) {
        return nlohmann::json(py::cast<float>(source));
    };

    // decimal.Decimal is not serializable
    py::object Decimal = py::module_::import("decimal").attr("Decimal");
    py::object o       = Decimal("1.0");
    EXPECT_EQ(pymrc::cast_from_pyobject(o, handler_fn), nlohmann::json(1.0));

• Add JSONValues container class which is an immutable container for holding Python values as nlohmann::json objects if possible, and as pybind11::object otherwise. The container can be copied and moved, but the underlying nlohmann::json object is immutable.

• Updates nlohmann_json from 3.9 to 3.11 for patch_inplace method.

• Incorporates ideas from @drobison00's PR Update PythonObjectCache to support get and pop operations, update utils to allow passing of cached python objects. #417 with three key differences:

  1. Changes to the cast_from_pyobject are opt-in when unserializable_handler_fn is provided, otherwise there is no behavior change to the method.
  2. Unserializable objects are stored in JSONValues rather than a global cache.
  3. Does not rely on parsing the place-holder values.

This PR is related to nv-morpheus/Morpheus#1560

Checklist

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

[codecov]

Codecov Report

Merging #455 (64f7459) into branch-24.06 (bd7955e) will increase coverage by 0.09%.
The diff coverage is 88.70%.

Additional details and impacted files

@@               Coverage Diff                @@
##           branch-24.06     #455      +/-   ##
================================================
+ Coverage         73.68%   73.77%   +0.09%     
================================================
  Files               400      402       +2     
  Lines             14275    14395     +120     
  Branches           1113     1129      +16     
================================================
+ Hits              10518    10620     +102     
- Misses             3757     3775      +18     

Flag	Coverage Δ
cpp	70.39% <94.01%> (+0.16%)	⬆️
py	41.28% <2.41%> (-0.46%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files	Coverage Δ
...mrc/_pymrc/include/pymrc/utilities/json_values.hpp	100.00% <100.00%> (ø)
...rc/_pymrc/include/pymrc/utilities/object_cache.hpp	0.00% <ø> (ø)
python/mrc/_pymrc/src/utils.cpp	87.50% <100.00%> (+1.95%)	⬆️
python/mrc/_pymrc/src/utilities/json_values.cpp	87.61% <87.61%> (ø)

... and 4 files with indirect coverage changes

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[mdemoret-nv]

/merge