Document `explicit-progress` (Set/Get Progress from Code)

[pyranota]

Blocking factor is that python documentation does not compile:

pdoc --template template --output-dir /tmp wmill --force\
 && sed -i -e "/^title: /s/title: .*/title: Python Client/" /tmp/wmill/client.md\
 && mv /tmp/wmill/client.md src/pages/python.md
usage: pdoc [-o DIR] [-d {markdown,google,numpy,restructuredtext}] [--include-undocumented | --no-include-undocumented]
            [-e module=url] [--favicon URL] [--footer-text TEXT] [--logo URL] [--logo-link URL] [--math | --no-math]
            [--mermaid | --no-mermaid] [--search | --no-search] [--show-source | --no-show-source] [-t DIR] [-h HOST]
            [-p PORT] [-n] [--help] [--version]
            [module ...]
pdoc: error: unrecognized arguments: --force

https://github.com/windmill-labs/windmilldocs?tab=readme-ov-file#regenerate-python-documentation

[hcourdent]

Looks good to me!

[pyranota]

I will move it from CORE-CONCEPTS to ADVANCED-FEATURES and we can merge if everything is fine.

[pyranota]

Ready to merge