Store overrides in platform-specific perference dirs

[atrauzzi]

Is there any way that studio can store the list of packages that are being overridden in the platform-specific user preferences dir rather than a json file in the project root?

I'd probably just end up adding studio.json to .gitignore as that path is going to vary between users and platforms:

• /Users/bill (macOS)
• /home/sally (linux)
• C:\Users\pat001\Documents\github (Windows)

Doing something like this would really lock in a similar convention to npm and lower the cognitive overhead of this utility. At which point -- studio.json can pretty much be managed behind the scenes!

cc. https://github.com/composer/composer/issues/7064#issuecomment-364472602