Cache location change option

[MystikalE]

Describe the solution you'd like
I am using all of my temp files and cache files on HDD's rather than SSD or C disk in my case.

Describe alternatives you've considered
I'd like an option to change the program's cache location rather than default of %APPDATA% folder.

[SO9010]

Starting to have a look now.

[jacksongoode]

I think we could enable this pretty easy, the tricky bit might be making sure the migration works well.

[SO9010]

Yes I agree I had a bit of time to start trying to implement it earlier, but didn't get far so if you want to start it I'm happy to work on that!

[Self-Perfection]

FWIW psst respects $XDG_CACHE_HOME env var.

Thus it is possible to change cache location on GNU/Linux by running it like this:

XDG_CACHE_HOME=/some/dir psst-gui

Unfortunately this approach leads to duplication of fontconfig cache.

Or just symlink the cache to desired location:

mv -v ~/.cache/Psst/ /tmp/psst_cache
ln -sv /tmp/psst_cache/ ~/.cache/Psst

Windows supports symlinks as well as MacOS / Linux, but I do not know how to create them on Windows.