Python: Prevents LLMs from stripping complex function names - #4366

…t#4366)

### Motivation and Context

When using the `StepwisePlanner` planner along with core skills, for
example `TextMemorySkill`, the LLMs tend to plans with function names
stripped down to the name without the skill name. This makes the plan
fail with an exception like:

`Error invoking action recall: (<ErrorCodes.UnknownError: -1>, "The
function 'recall' was not found.", None)`

This error is because the completion returned by the planner prompt does
not include the fully structured skill function name. Ex.: instead of
returning `_GLOBAL_FUNCTIONS_.recall` it returns `recall` or
`GLOBAL_FUNCTIONS.recall`.

This is somehow relates microsoft#3237

### Description


This change instructs the LLM to keep the skill function name unchanged
in its response by adding an example that includes `_` in the name. This
approach mimics how the `SequentialPlanner` solves this same issue.

### Contribution Checklist

- [X] The code builds clean without any errors or warnings
- [X] The PR follows the [SK Contribution
Guidelines](https://github.com/microsoft/semantic-kernel/blob/main/CONTRIBUTING.md)
and the [pre-submission formatting
script](https://github.com/microsoft/semantic-kernel/blob/main/CONTRIBUTING.md#development-scripts)
raises no violations
- [X] All unit tests pass, and I have added new tests where possible
- [X] I didn't break anyone 😄