Add more docstring examples

I think it would be helpful to have more example in docstrings on how to use various functions and methods exposed in Pyodide. The general approach could be to,

• have a short description documenting the function/method/class and its parameters/return value
• include an example, ideally that is run as a doctest (we need to figure out how to do this) otherwise those will get outdated in time
• link to the user manual for more details, when it makes sense

This is related to #1498

Python API

(looking at the API documentation)

• pyodide.CodeRunner
• pyodide.JsProxy
• console.Console
• console.ConsoleFuture
• console.repr_shorten
• pyodide.create_once_callable
• pyodide.create_proxy
• pyodide.destroy_proxies
• pyodide.eval_code
• pyodide.eval_code_async
• pyodide.find_imports
• pyodide.open_url
• pyodide.register_js_module
• pyodide.should_quiet
• pyodide.to_js
• pyodide.unregister_js_module
• class webloop.WebLoop

Micropip API

• micropip.install

JS API

It's still unclear to me how dostring examples should look like in JS and whether they could be run as doctests. Will open a separate issue.

• pyodide.isPyProxy
• pyodide.loadPackage
• pyodide.loadPackagesFromImports: the is a verbal example, but I think it would be easier to read it as code.
• pyodide.registerComlink
• pyodide.registerJsModule
• pyodide.runPython
• pyodide.runPythonAsync
• pyodide.setStandardStreams also misses argument description
• pyodide.toPy
• pyodide.PyBuffer: there is an example but I find it quite complex
• PyProxy (and possibly its methods)