TST Add a fixture for testing wheels from external URL

[ryanking13]

Adds a pytest fixture that simplifies installing a wheel from external URL.

This replaces a common pattern we use when testing a wheel, which is:

with spawn_web_server(TEST_WHEEL_DIR) as server:
        server_hostname, server_port, _ = server
        url = f"http://{server_hostname}:{server_port}/"
        wheel_url = url+"....whl"

        micropip.install(wheel_url)

with:

pkg = test_wheel_catalog.get("<pkg_name>")
pkg.url
micropip.install(pkg_url)

[hoodmane]

Thanks for doing this maintenance work @ryanking13!

[hoodmane]

Maybe while we're att it we should transform this one to use @run_in_pyodide:

Suggested change

	selenium.run_js(
	f"""
	await pyodide.runPythonAsync(`
	import micropip
	await micropip.install('{url}')
	import snowballstemmer
	`);
	"""
	)
	@run_in_pyodide
	def install_from_url(url):
	import micropip
	await micropip.install(url)
	import snowballstemmer
	install_from_url(url)

[ryanking13]

Thanks for the review!