Change order to search for GPG configuration directory

Up to now, KMyMoney used a more or less hardcoded set of directories to find out, where gpg has its home directory. The order used is not ideal to be used in all operating system environments.

This code change makes sure that the directory information provided by GPG is searched first, then the directories returned by QStandardPaths::AppDataLocation and as a last resort the QStandardPaths::HomeLocation.

Within these directories a search inside sub-directories ".gnupg" and "gnupg" is also performed. This does not change to the original implementation.

BUG:399230