Move global state to OS dependent directories

[me-nx]

Merge base version

• MC Version: 1.16.1, can be cherry-picked to other branches
• SpeedRunIGT Version: 16.1 (future)

Changes

Move global state from ~/speedrunigt to appropriate OS dependent paths to avoid polluting the home directory.

Context

I've seen #105, but:
a) there has been no progress on the linked fabric issue for the last year
b) that issue concerns cache directories, which speedrunigt shouldn't use for storing fonts & categories (for example on linux ~/.cache may be cleared at any time).

This PR moves the global state to %APPDATA% on Windows, an XDG mandated data directory on Linux, and ~/Library/Application Support/ on OS X.

I've quickly tested the changes on Linux and Windows.

Drawbacks

• Possible user confusion?
• Old versions of the mod will continue to use the old directory

Alternatives

Instead of moving the directory the mod could check if the new directory exists, else fall back to the old ~/speedrunigt path if it exists.

Feel free to reject if you don't think this is important enough.

[me-nx]

@tildejustin ping since u wrote that PR

[tildejustin]

mine was more concerned with allowing srigt to work with fabric loader sandbox but nothing has happened with that for a while. happy for this to supercede it, esp b/c it looks like you know what you're doing with what should go where more on different OSs more than me :P

[me-nx]

Since this may hurt discoverability me-nx/SpeedRunIGT@a97234d adds a button to open the custom categories folder (like the one for the fonts folder), so that the user doesn't have to find it themselves. LMK if u want it in this PR