feat: add optional outListingFile config property that copies model listing JSON file as post-generate step

[chrispcampbell]

Fixes #492

This adds a new optional outListingFile property to UserConfig (as used in sde.config.js), which simplifies the process of copying the model listing file to a specific location, like a source code directory.

The one place where this was relevant was the new house-game example. I was able to simplify the sde.config.js file for that project to use this new property instead of the old workaround, which was a custom plugin that copied the file.

As part of this, I updated the build package tests to remove the sde-prep directory between runs, and moved the build-dev and build-prod tests into separate directories, since before there was a chance that they would share the same sde-prep directory, which could lead to race conditions.