prepare test fixtures consisting of a package and module with relative & absolute import
test scripting server runs with these variations
- from package or from module
- with or without reloader
the server code is based off servertest.py

python doesn't have an obvious way to reveal the original command and module name, so we check the __main__ module for __package__ and infer it's a module running as a script unless the value is None, which implies a file path was provided
modules running as scripts are invoked with -m flags
packages running with scripts have base filename __main__.py
from this we recreate an invocation

these will support top-level module script test cases

arrange package script to import submodule
new test cases check the top-level module name is prepared correctly
module tests cases are renamed submodule for clarity

refactor function to return main script arguments

__main__ can be imported