Respect XDG_STATE_HOME when storing history file

[Biont]

This is a rather new addition to the basedir-spec that looks useful for us.

See the raw specification and some dicussion here

I think it makes sense given that the current location in .cache can imply that -since it is called "cache"- it could be deleted at any point without causing any interruption save for a bit of added latency. That's not the case: It would absolutely be an interruption since all launcher history is now missing and must rebuild. So saving this under a different namespace sounds reasonable.