1st pass at dev instructions for getting started with the Python SDK

[cleemullins]

This pull request adds a comprehensive developer setup guide in the new DevInstructions.md file. The document provides step-by-step instructions for setting up the development environment, including prerequisites, environment setup, dependency installation, testing, and running local samples. It also includes instructions for setting up Dev Tunnels and creating a new agent in Azure Portal.

Development environment setup:

• Added detailed instructions for cloning the repository, installing VS Code and Python, setting up a virtual environment, and configuring VS Code for Python development.
• Provided steps for installing project dependencies, creating symlinks for editable libraries, and running unit tests with pytest.

Dev Tunnels and Azure Agent setup:

• Included a section on installing and configuring Dev Tunnels, with commands for tunnel creation and hosting.
• Added instructions for creating a new Agent (Bot) in the Azure Portal and configuring its messaging endpoint to use the Dev Tunnel.

Local testing and tooling:

• Described how to install and use the Teams Toolkit Playground for local agent testing, and how to run sample agents from the test_samples folder in VS Code.

To-do items:

• Listed future improvements such as adding VS Code settings, launch configurations, and cleaning up old branches.

[rido-min]

Should we have these instructions in the /agents repo? most of the steps are applicable to all languages

[rodrigobr-msft]

For open source Python, I believe being agnostic to the tools and setup of the developers leads to a better experience overall. I like the idea of having a separate document or section for utilizing VSCode, but pushing it as the way to do things might lead to confusion now or later (with potentially future changes that bias more and more towards using that particular IDE). I am open to discussing this though. edit: Oops, I added my comments to the commit instead.

[rodrigobr-msft]

I added my comments to the commit instead of the PR. Adding them here.