Python: Grab function_name from kwargs if present in ProcessStepEdgeBuilder

[moonbox3]

Motivation and Context

In the ProcessStepEdgeBuilder, we allow one to pass in a target of type "ProcessFunctionTargetBuilder | ProcessStepBuilder". If the target isinstance(target, ProcessStepBuilder), we construct the ProcessFunctionTargetBuilder. We weren't grabbing the function_name from the kwargs if it was presented, resulting in an exception that the function_name needs to be provided because multiple kernel functions exist.

Description

This PR:

• correctly passes in the function_name kwargs, if present.
• Adds a unit test to exercise functionality

Contribution Checklist

• The code builds clean without any errors or warnings
• The PR follows the SK Contribution Guidelines and the pre-submission formatting script raises no violations
• All unit tests pass, and I have added new tests where possible
• I didn't break anyone 😄

[markwallace-microsoft]

Python Test Coverage Report •

File	Stmts	Miss	Cover	Missing
semantic_kernel/processes
process_step_edge_builder.py	35	3	91%	43, 60, 70
TOTAL	16709	1778	89%

Python Unit Test Overview

Tests	Skipped	Failures	Errors	Time
3002	4 💤	0 ❌	0 🔥	1m 15s ⏱️