describe how to migrate a Mixxx profile (database, settings etc.) to a new PC / new Mixxx installation

[ronso0]

This a FAQ, either users ask in advance, or they already moved the settings but messed something up.

There is some info floating around in the forums, as well as the wiki How can I move my music to another folder or hard drive without losing information like BPM or cue points?, we should make the answer more accessible, maybe add some background info / troubleshooting steps.

I thought about adding it to either Preferences > Library, and/or add a paragraph to Library which gives a link in the doc tree (so it can be found easily) and put the actual info to Advanced Topics or Preferences > Library.

The tutorial itself would be something along the lines I wrote here mixxxdj/mixxx#12254 (comment)