Python: Restructure samples into new folders to make things more clea…

…r. (microsoft#6116)

### Motivation and Context

All previous samples were either in kernel syntax or a separate
notebooks folder. The goal is to make the samples easier to understand
and have a better structure.

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### Description

The PR restructures the kernel syntax examples into new folders:
concepts (with subfolders for previous syntax examples), demos,
getting_started, and learn_resources.
- Closes microsoft#6119 
- Adds a new concept/function example for understanding kernel
arguments.
- Updates the bookings plugin

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### Contribution Checklist

<!-- Before submitting this PR, please make sure: -->

- [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 😄

README.md

@@ -90,7 +90,7 @@ The fastest way to learn how to use Semantic Kernel is with our C# and Python Ju
 demonstrate how to use Semantic Kernel with code snippets that you can run with a push of a button.
 
 - [Getting Started with C# notebook](dotnet/notebooks/00-getting-started.ipynb)
-- [Getting Started with Python notebook](python/notebooks/00-getting-started.ipynb)
+- [Getting Started with Python notebook](python/samples/getting_started/00-getting-started.ipynb)
 
 Once you've finished the getting started notebooks, you can then check out the main walkthroughs
 on our Learn site. Each sample comes with a completed C# and Python project that you can run locally.