Python: slight improvements in kernel and function result content, sample of local function calling with Nexus Raven

[eavanvalkenburg]

Motivation and Context

This introduces a sample that uses function calling with a local model, Nexus Raven V2, in this case using the API, but the same model can be loaded using the Hugging Face Connection, the class here is highly adapted and specific to Nexus including parsing the returned function call value, into FunctionCallContent and then running that.
It then returns one or more ChatMessageContents with the function call content and function result content which can then be shared with a OpenAI call.

Error handling improvements:

• python/semantic_kernel/contents/chat_history.py: Improved error logging when parsing prompts as XML fails.
• python/semantic_kernel/contents/function_result_content.py: Removed field validator for result and allow result to be any value, instead of casting everything to string. [1] [2] [3] [4]

Minor changes:

• python/semantic_kernel/core_plugins/math_plugin.py: Removed some docstrings for clarity. [1] [2]
• python/semantic_kernel/functions/kernel_function_from_prompt.py: Changed the order of condition checks for better readability.
• python/semantic_kernel/kernel.py: Added functionality to update kernel arguments in invoke_stream method and made function_name and plugin_name optional in invoke_prompt method. [1] [2] [3] [4] [5]

Closes #6804
Closes #6944

Description

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 3.10 Test Coverage Report •

File	Stmts	Miss	Cover	Missing
semantic_kernel
kernel.py	157	72	54%	145, 152–161, 199–207, 278–314, 342, 344–348, 364–408, 412–423
semantic_kernel/contents
chat_message_content.py	124	1	99%	234
function_result_content.py	73	21	71%	57, 62, 66, 81, 96, 99, 101, 103–109, 126, 131, 138–142
semantic_kernel/functions
kernel_function_from_prompt.py	154	7	95%	165–166, 180, 200, 218, 238, 321
TOTAL	6686	781	88%

Python 3.10 Unit Test Overview

Tests	Skipped	Failures	Errors	Time
1567	1 💤	0 ❌	0 🔥	18.949s ⏱️