XDG Support

[MarcinWieczorek]

Hello, Thank you for maintaining such a wonderful project. I noticed wpscan creates a directory in $HOME, which creates clutter. There is a standard for that: https://specifications.freedesktop.org/basedir-spec/basedir-spec-latest.html I think that XDG_DATA_HOME would be good as an alternative (in most cases that would be ~/.local/share/wpscan/db. Some migration and backward compatibility would be required, but I hope someone finds time for that.

The issue seems to be here: https://github.com/wpscanteam/wpscan/blob/f61c55b350a426dd336ae2cfc9607a0f9e76ecea/lib/wpscan.rb#L40

Thanks!