Error on Parameter default kwarg usage for input annotations

[elliotgunton]

Pull Request Checklist

• Fixes Input Parameter annotations should only be able to set default via standard Python #812
• Tests added
• Documentation/examples added
• Good commit messages and/or PR title

Description of PR
Currently, using the default kwarg for a Parameter in an input Annotation or Hera's Pydantic Input class logs a warning message, added in #1102. This PR makes the code path raise an error, which can be supressed using the suppress_parameter_default_error experimental feature flag for 1 minor version until it is removed.

[samj1912]

Should this be an experimental flag?

[elliotgunton]

What do you mean? Should the error be supressed another way?

[samj1912]

Yeah, I think so. This is a flag but not really an experiment.

[elliotgunton]

I was intending this to only be a one-off flag for 1 minor version, so I'd rather not add another feature flag syntax just for 1 flag for 1 version (and then have to keep it around). Plus the supression flag is a nicety instead of the intended purpose of "experimental" letting us make breaking changes, but Annotated became a mainstay so I understand the need in this case.

In any case, the global_config.experimental_features dictionary should be able to hold whatever we need it to hold related to any experimental features - we haven't put any enforced rules on it.

hera/src/hera/shared/_global_config.py

Lines 77 to 78 in 77a214d

	experimental_features: Dict[str, bool] = field(default_factory=lambda: defaultdict(bool))
	"""an indicator holder for any Hera experimental features to use"""

[flaviuvadan]

FWIW I think experimental flag is ok as long as we have a clear deadline/version by which we're going to remove this. Small but do we need a warning and a ValueError? I sense the warning will get lost when the exception is raised

[elliotgunton]

@flaviuvadan Good idea - I can add an explicit version (5.18?) in the warning and error text?

the warning will get lost

For the first time seeing the error, yes, the warning will probably not be seen, but then after turning the flag on, we still want the user to see the logged warning.