[FEATURE] use an XDG directory for storing lyrics #651

Is your feature request related to a problem? Please describe.
I do not like .lyrics forlder just sitting there in $HOME by default.
Yes, one is able to put it elsewhere but that should not be nescessary

Describe the solution you'd like
Right now the project uses XDG_CONFIG_HOME

I suggest the lyrics are written to XDG_CACHE_HOME.
The current state could be a fallback.

Describe alternatives you've considered
The alternative is not using them, which is the current state

Additional context
Could solve #574