Python: planner love

[eavanvalkenburg]

Motivation and Context

Based on #5474 went into the using-the-planner notebook and made sure it works with the latest code.

Description

Moved all the planners to use '-' in line with the current work on new templates and planners, once that is in several extension classes can be changed.
Encountered several small bugs left over from changes over the last months.
Got through the whole notebook with results.

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 3.8 Test Coverage Report •

File	Stmts	Miss	Cover	Missing
semantic_kernel
kernel.py	324	29	91%	195–199, 201–205, 207–211, 219–221, 240, 246, 248–252, 254–258, 260–265, 267, 312–316, 333–338, 345, 349–353, 366, 625
semantic_kernel/planners
basic_planner.py	64	48	25%	19–21, 24, 135, 143–169, 181–204, 213–243
plan.py	234	46	80%	48, 151–155, 187, 202–212, 246, 250, 258–259, 269–272, 287, 292–295, 310, 313–318, 336, 341, 344, 346, 353, 366–368, 373–377
semantic_kernel/planners/sequential_planner
sequential_planner.py	65	6	91%	71, 75, 106, 122, 131–132
sequential_planner_parser.py	77	12	84%	63–72, 92, 115–118
semantic_kernel/planners/stepwise_planner
stepwise_planner.py	223	140	37%	12, 95, 109–127, 136–206, 227–230, 238–249, 252, 260–275, 278–314, 317–345, 348–353, 356–368, 371–374, 387–399
TOTAL	5227	999	81%

Python 3.8 Unit Test Overview

Tests	Skipped	Failures	Errors	Time
1131	11 💤	0 ❌	0 🔥	20.122s ⏱️

[moonbox3]

Looks great, a few small comments.

[juliomenendez]

Nice cleanup! LGTM