[BUG]: Fix incorrect typing for the @stage and @source decorators

[mdemoret-nv]

Version

24.06

Which installation method(s) does this occur on?

Source

Describe the bug.

When creating a stage using the @stage decorator, python linters and language services report errors when using these stages because the config type is unexpected or keyword arguments are missing.

A quick prototype had good results using ParamSpec object. For example:

_InputT = typing.TypeVar('_InputT')
_OutputT = typing.TypeVar('_OutputT')
_P = typing.ParamSpec('_P')

def stage(on_data_fn: typing.Callable[typing.Concatenate[_InputT, _P], _OutputT] = None,
          *,
          name: str = None,
          accept_type: type = None,
          compute_schema_fn: ComputeSchemaType = None,
          needed_columns: dict[str, TypeId] = None):

Minimum reproducible example

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Relevant log output

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Full env printout

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Other/Misc.

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Code of Conduct

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• I have searched the open bugs and have found no duplicates for this bug report