Add tests for example packages in our python packaging guide

[ucodery]

After #248 we will have real example projects to pull from in docs. These projects should all be tested so that they remain a set of accurate and meaningful examples.

Each project should be tested via a nox session which will verify that each can be: built, installed, imported, run

This nox session should also be run during CI.

[lwasser]

also please see our examplePy repo where i began to create example packages! And #252 ... we've come a long way since i started working on examplePy which is so so awesome! 💟 community 💟

[lwasser]

i'm pulling this from our help wanted board as well until this issue is more specific so someone could work on it. @ucodery if you have time to add a bit more detail that would be wonderful!

[ucodery]

Ideally this guide would not host any example projects that

1. do not build a distribution artifact
2. are not installable or at all usable (if it installs but gives SyntaxError 100% of the time)
3. does not pass its own test suite
4. does not pass its own static analysis or other pre/post commit checks
5. cannot build its own documentation

In order to guarantee all of this, each of these cleanliness checks needs to be done for each example project as part of the larger guide's checks.

[jrrickerson]

I'm going to try taking a crack at this during the PyCon US 2025 sprints.