(Fusion Exporter) os module missing

[HunterBarclay]

Description

A couple of users have encountered a bug in which their Fusion exporter addins crash due to the following:

ImportError: cannot import name '__file__' from 'os' (unknown location)

How to Reproduce

I've found that updating Fusion generally causes this but the versions in which we've updated to has varied. The latest version of Fusion in which we haven't been able to reproduce the bug was in 2.0.16490 on Windows 10.

The most effective way for reproducing it, we've found so far, is by updating Fusion. We also haven't been able to reproduce it on MacOS yet.

Current Work Arounds

Both @BrandonPacewic and I have found that after starting the addin in debug mode then restarting Fusion 360, the addin begins to work as expected and the issue is no longer reproducible. This worked in #948 but failed with another user on Discord.