Review and simplify argparse docs

[savannahostrowski]

The argparse docs have become pretty lengthy. This is in part due to the examples, which are somewhat duplicative of the tutorial. I'd like to go through the docs to see if we can dedupe and pare things down to make them more readable.

Linked PRs

• GH-124478: Cleanup argparse documentation #124877
• [3.13] GH-124478: Cleanup argparse documentation (GH-124877) #125162
• [3.12] GH-124478: Cleanup argparse documentation (GH-124877) #125164

[rruuaanng]

I believe that argparse does not need to display sample code, only the public API needs to be shown.

[hugovk]

I disagree, argparse is part of the public API and sample code is useful to show how to use it.