ref(grouping): Add python multiprocessing context line test inputs

[lobsterkatie]

As a preliminary step in the process of fixing our under-grouping of Python multiprocess events, this adds more examples of the problem to the grouping inputs. Specifically, it adds:

• An input which reflects the different kwargs used on Windows.
• An input which uses (ill-advised, but still entirely possible) grouping rules to unignore the problematic frames.
• An input which combines both of the above.

It also renames the existing input, to differentiate it from the Windows version.