Separate files in pythonFiles by task

[brettcannon]

When debugging, the whole of pythonFiles is put on to sys.path via PYTHONPATH. This led to an issue requiring a hotfix due to the tests package accidentally being shipped in the .vsix. Unfortunately this will continue to be a problem for any code placed in that directory.

To help minimize future clashes with user code during debugging, it would be best to separate all code in that directory into thematic directories to minimize the chance of shadowing user's code. This is somewhat already done when dependencies are installed into pythonFiles/lib/python instead of into pythonFiles directly.

[DonJayamanne]

Shouldn't we also consider deleting sys.path[0] from our code, before running user code, this way the current path will not be added to sys.path preventing such future issues?
That feels like a future proof solution