Only reassign waterfall step name only if the step doesn't have a name

[Zerryth]

Fixes #670

Description

In WaterfallDialog.get_step_name method, it uses __qualname__ dunder method to get a unique name for the waterfall step

    def get_step_name(self, index: int) -> str:
        """
        Give the waterfall step a unique name
        """
        step_name = self._steps[index].__qualname__

        if not step_name or ">" in step_name:
            step_name = f"Step{index + 1}of{len(self._steps)}"

        return step_name

The method's intention is to only create and assign a name if the waterfall step is anonymous, which commonplace in C# and JS SDKs.

However, because the full qualname is given, ">" is present, even if waterfall steps defined with a name (i.e. no anonymous methods used to define steps). This results in an overapplication of renaming waterfall step names, even if the step already has a name to begin with.

Click to see more detailed example

Create a waterfall dialog that has one step, which is defined by a function named get_user_name.

async def get_user_name(step):
   # do stuff
   return Dialog.end_of_turn

dialog = WaterfallDialog("my_dialog", steps=[get_user_name])

Expected Step Name from get_step_name

<full_qualname_prefix>+ .get_user_name

Actual Name from get_step_name

Step1of1

• It's been reassigned a name, even though the step already had a name

Specific Changes

• Will only create and assign a step name if waterfall step_name is not present or if ends with <lambda>

Testing

• Test unit test added to verify telemetry works properly in waterfall dialogs