Improved type-hints for stage and source decorators (nv-morpheus#1831)

* Improved type hints for both the input parameters and the return types

Closes  nv-morpheus#1812

## By Submitting this PR I confirm:
- I am familiar with the [Contributing Guidelines](https://github.com/nv-morpheus/Morpheus/blob/main/docs/source/developer_guide/contributing.md).
- When the PR is ready for review, new or existing tests cover these changes.
- When the PR is ready for review, the documentation is up to date with these changes.

Authors:
  - David Gardner (https://github.com/dagardner-nv)

Approvers:
  - Michael Demoret (https://github.com/mdemoret-nv)

URL: nv-morpheus#1831

morpheus/pipeline/stage_decorator.py

@@ -31,7 +31,12 @@
 from morpheus.messages import MultiMessage
 
 logger = logging.getLogger(__name__)
-GeneratorType = typing.Callable[..., collections.abc.Iterator[typing.Any]]
+
+_InputT = typing.TypeVar('_InputT')
+_OutputT = typing.TypeVar('_OutputT')
+_P = typing.ParamSpec('_P')
+
+GeneratorType = typing.Callable[_P, collections.abc.Iterator[_OutputT]]
 ComputeSchemaType = typing.Callable[[_pipeline.StageSchema], None]
 
 
@@ -134,7 +139,12 @@ class PreAllocatedWrappedFunctionStage(_pipeline.PreallocatorMixin, WrappedFunct
     """
 
 
-def source(gen_fn: GeneratorType = None, *, name: str = None, compute_schema_fn: ComputeSchemaType = None):
+def source(
+    gen_fn: GeneratorType = None,
+    *,
+    name: str = None,
+    compute_schema_fn: ComputeSchemaType = None
+) -> typing.Callable[typing.Concatenate[Config, _P], WrappedFunctionSourceStage]:
     """
     Decorator for wrapping a function as a source stage. The function must be a generator method, and provide a
     provide a return type annotation.
@@ -162,7 +172,7 @@ def source(gen_fn: GeneratorType = None, *, name: str = None, compute_schema_fn:
     # Use wraps to ensure user's don't lose their function name and docstrinsgs, however we do want to override the
     # annotations to reflect that the returned function requires a config and returns a stage
     @functools.wraps(gen_fn, assigned=('__module__', '__name__', '__qualname__', '__doc__'))
-    def wrapper(config: Config, **kwargs) -> WrappedFunctionSourceStage:
+    def wrapper(config: Config, **kwargs: _P.kwargs) -> WrappedFunctionSourceStage:
         nonlocal name
         nonlocal compute_schema_fn
 
@@ -271,12 +281,15 @@ def _build_single(self, builder: mrc.Builder, input_node: mrc.SegmentObject) ->
         return node
 
 
-def stage(on_data_fn: typing.Callable = None,
+DecoratedStageType = typing.Callable[typing.Concatenate[Config, _P], WrappedFunctionStage]
+
+
+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):
+          needed_columns: dict[str, TypeId] = None) -> DecoratedStageType:
     """
     Decorator for wrapping a function as a stage. The function must receive at least one argument, the first argument
     must be the incoming message, and must return a value.
@@ -317,7 +330,7 @@ def stage(on_data_fn: typing.Callable = None,
     # Use wraps to ensure user's don't lose their function name and docstrinsgs, however we do want to override the
     # annotations to reflect that the returned function requires a config and returns a stage
     @functools.wraps(on_data_fn, assigned=('__module__', '__name__', '__qualname__', '__doc__'))
-    def wrapper(config: Config, **kwargs) -> WrappedFunctionStage:
+    def wrapper(config: Config, **kwargs: _P.kwargs) -> WrappedFunctionStage:
         nonlocal name
         nonlocal accept_type
         nonlocal compute_schema_fn