[REQUEST] Store data in ApplicationData directory

[Anti-Apple4life]

Is your feature request related to a problem? Please describe.

Whenever osuplayer is run, the data folder is created in the working directory. This is frustrating because it makes moving to new versions harder.

Describe the solution you'd like

The solution to this problem would be to store the data folder in the AppData/Roaming folder on Windows or the ~/.local/share/ directory on Linux.

Additional context

My C# is a bit rusty, but you could use the code:

Path.Join(Environment.GetFolderPath(Environment.SpecialFolder.ApplicationData), "osuplayer");

to get ~/.local/share/osuplayer on Linux and AppData/Roaming/osuplayer on Windows.