Python: Refactoring. Use get_function and get_plugin.

[stefan521]

Motivation and Context

Refactoring some of the code following this advice from the maintainers.

Description

Look up kernel functions and plugins with the get_function and get_plugin method. Removed the unused DEFAULT_CHAT_SYSTEM_PROMPT

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 😄

[stefan521]

@microsoft-github-policy-service agree

…

On Thu, May 23, 2024 at 8:43 PM microsoft-github-policy-service[bot] < ***@***.***> wrote: @stefan521 <https://github.com/stefan521> the command you issued was incorrect. Please try again. Examples are: @microsoft-github-policy-service agree and @microsoft-github-policy-service agree company="your company" — Reply to this email directly, view it on GitHub <#6382 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AG6PSU3N2GYDTN6ZMGDCVZTZDZBELAVCNFSM6AAAAABIGI3BPGVHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHMZDCMRXHA4TSMBTGY> . You are receiving this because you were mentioned.Message ID: ***@***.***>

[stefan521]

@microsoft-github-policy-service agree

…

On Thu, May 23, 2024 at 8:54 PM microsoft-github-policy-service[bot] < ***@***.***> wrote: @stefan521 <https://github.com/stefan521> the command you issued was incorrect. Please try again. Examples are: @microsoft-github-policy-service agree and @microsoft-github-policy-service agree company="your company" — Reply to this email directly, view it on GitHub <#6382 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AG6PSU74QPOHQWSZZ654CT3ZDZCQ3AVCNFSM6AAAAABIGI3BPGVHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHMZDCMRXHEYTMMRYGU> . You are receiving this because you were mentioned.Message ID: ***@***.***>

[markwallace-microsoft]

Python 3.10 Test Coverage Report •

File	Stmts	Miss	Cover	Missing
TOTAL	6078	870	86%

report-only-changed-files is enabled. No files were changed during this commit :)

Python 3.10 Unit Test Overview

Tests	Skipped	Failures	Errors	Time
1374	1 💤	0 ❌	0 🔥	13.682s ⏱️

[moonbox3]

LGTM. My small nit is to use named args to make it more clear when reading:

function = kernel.get_function(plugin_name=<name>, function_name=<name>)

May just be my style preference. :)

[stefan521]

LGTM. My small nit is to use named args to make it more clear when reading:

function = kernel.get_function(plugin_name=<name>, function_name=<name>)

May just be my style preference. :)

That's a good shout. I've named them.

[moonbox3]

@stefan521 please run a Black format in the python directory to fix the lint issues.