Add Pydantic V1 IO models for use with Hera Runner

[elliotgunton]

Pull Request Checklist

• Part of Improve Hera I/O models #858
• Tests added
• Documentation/examples added See Add pydantic IO docs #939
• Good commit messages and/or PR title

Description of PR
Currently hera i/o with annotated params can become extremely verbose. The output syntax is especially error-prone.

This PR introduces custom Input/Output BaseModels for users to subclass, which allow a cleaner arrangement of inputs and outputs for functions. These are available under the script_pydantic_io experimental feature flag.

With these Pydantic input/output models, the following should be noted:

• duplicated param names (for normal Parameters as well as the new models) are now detected in Hera rather than when linted by Argo (as well as duplicated artifact names). Parameters and Artifacts having the same name is legal in the Argo spec as they exist in different scopes e.g.

...
      inputs:
        parameters:
          - name: my-name
            default: test
        artifacts:
          - name: my-name
            path: /tmp
            optional: true
...

• exit_code and result are reserved attributes for the RunnerOutput. A user trying to use their own parameters with these names would have to be specified with an annotated parameter e.g. my_exit_code: Annotated[int, Parameter(name="exit_code")] (TBC with a test)
• Scripts cannot have a return tuple containing any RunnerOutput to avoid multiple exit_codes being specified. @samj1912 / @flaviuvadan this is up for debate but I think would encourage better practices to discourage tuples and have a single script template outputting a single RunnerOutput subclass, and it keeps the logic clearer from the Hera side. Users can still use inline output parameters alongside the RunnerOutput return annotation
• Multiple input parameters when using a RunnerInput in the function params is not legal
• A RunnerInput's __fields__ as defined by pydantic are used to "explode" the input class into constituent parameters for the Argo spec. i.e. using the following class as an input param to a script function:

class MyInput(RunnerInput):
     my_input_str: str
     my_input_int: int

@script(constructor="runner")
def my_func(my_input: MyInput):
    ...

will create the script template my_func in yaml with Parameters my_input_str and my_input_int, NOT my_input, see the example

[codecov]

Codecov Report

Attention: 9 lines in your changes are missing coverage. Please review.

Comparison is base (b3fc378) 80.7% compared to head (a0dd261) 81.2%.
Report is 1 commits behind head on main.

❗ Current head a0dd261 differs from pull request most recent head 221ecae. Consider uploading reports for the commit 221ecae to get more accurate results

Files	Patch %	Lines
src/hera/workflows/runner.py	93.8%	1 Missing and 3 partials ⚠️
src/hera/workflows/io.py	95.2%	0 Missing and 3 partials ⚠️
src/hera/workflows/script.py	94.1%	1 Missing and 1 partial ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##            main    #920     +/-   ##
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+ Coverage   80.7%   81.2%   +0.4%     
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  Files         50      51      +1     
  Lines       3908    4045    +137     
  Branches     793     843     +50     
=======================================
+ Hits        3157    3287    +130     
- Misses       564     565      +1     
- Partials     187     193      +6     

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[samj1912]

@elliotgunton can you provide a brief examples/details in the PR description of the functionality that is currently enabled?

Specifically I am curious how we handle things when a user -

• has duplicate param names between a non annotated param/annotated param/normal param
• has duplicate names between params/artifacts (this should be valid?)
• has a parameter/artifact called output/exit code
• has multiple output return types
• has multiple input types
• how is the input object constructed from argo params
• I see we added support for defaults as well (is it also added back to the normal params apart from hera io models?)

Having that in the PR description would help future readers understand what is happening.

[elliotgunton]

Only one function param that is a RunnerInput subclass is allowed

[elliotgunton]

Only one RunnerOutput is allowed as the function return type. Note that we also haven't dealt with nested Annotated types above.

[elliotgunton]

@samj1912 ready for re-review! Self-reviewed to double check this PR stands on its own to implement for Pydantic V1 and signposted the single input/output we discussed 🚀