Use GameMaker's default location for the runner cache

[adam-coster]

When creating GameMaker builds via the Igor CLI, the cache location has to be specified. The Stitch runner defaults to a location within the project, which is convenient for being able to easily investigate the cache contents but means that the GameMaker IDE and Stitch use different caches.

The benefits to Stitch owning its own cache are pretty minimal, and the main cost is a sort of de-syncing between what the official GameMaker IDE and Stitch are doing.

It would be better if Stitch use the same location as the IDE.

• [ ] Change the default cache location to whatever GameMaker uses
• [ ] Determine what happens to the cache contents when the are "cleared", and update the cach-clear logic to first check the cache contents to see if they've already been cleared

[adam-coster]

It turns out that there's no way to infer the location of GameMaker's runner cache, since it is generated via some combination of random and non-random identifiers that can also change over time.