Draft: Fix output config persistence when EDID missing

Missing EDID configuration results in broken output configuration persistence, which in turns implies no restoring of scale.

Marked as draft for a number of reasons: a) the logic in OutputConfigurationStore::findOutput has changed a bit - I understand it better now, it seems to work for me, but I don't understand the original logic

b) there is a lot of code which seems to assume that there always is valid EDID data (which is not the case for my virtual machines, for instance, where it is empty), see warning log output and also see some auditing of ->edit(); I don't know what the best approach is to resolve that. Right now a lot of code (still) simply accesses the defaults.