Fix rez-python arg disordered

[davidlatwe]

Problem

When I run command

> rez-python -m pip list

It shows

Scripts\python.exe: No module named list

Which is weird since the module arg should be pip, so I print out the args that parsed into python.exe and it shows :

['scripts\python.exe', '-E', '-m', 'list', 'pip']

As you can see, pip has been parsed as FILE arg and then appended behind other args that are unrecognized by the rez-python arg-parser.

Fix

Instead of rearranging arguments by what are recognized and what not, just pass them all directly into python executable. Since it looks like we only need parser to run script file auto-completion.