Improve Ghostwriter for max() builtin and similar signatures

[Zac-HD]

Some builtin functions don't support inspect.signature(), which the ghostwriter works around by trying to parse their docstring with regex:

hypothesis/hypothesis-python/src/hypothesis/extra/ghostwriter.py

Lines 328 to 345 in 3226dd7

	if (
	isinstance(func, (types.BuiltinFunctionType, types.BuiltinMethodType))
	and hasattr(func, "__doc__")
	and isinstance(func.__doc__, str)
	):
	# inspect.signature doesn't work on all builtin functions or methods.
	# In such cases, including the operator module on Python 3.6, we can try
	# to reconstruct simple signatures from the docstring.
	pattern = rf"^{func.__name__}\(([a-z]+(, [a-z]+)*)(, \\)?\)"
	args = re.match(pattern, func.__doc__)
	if args is None:
	raise
	params = [
	# Note that we assume that the args are positional-only regardless of
	# whether the signature shows a `/`, because this is often the case.
	inspect.Parameter(name=name, kind=inspect.Parameter.POSITIONAL_ONLY)
	for name in args.group(1).split(", ")
	]

However, max.__doc__ highlights a few things not handled by the current pattern:

max(iterable, *[, default=obj, key=func]) -> value
max(arg1, arg2, *args, *[, key=func]) -> value

1. square brackets used to indicate optional arguments - we want to allow-but-ignore these
2. * indicating that following arguments are keyword-only - we should still assume that positional args are pos-only, but assuming that kwonly args are pos-only is silly
3. "handle" multiple signatures by using the first that we can understand - i.e. change "match first line" to "search all matching lines" and keep the first