Use QRegularExpression behind the same Qt version guard as
totalMemoryBytes() in availableMemoryBytes(), where a bare QRegExp
broke every Qt6 Linux build. hasAtLeastGiB() now treats a 0 reading
(unsupported platform or failed query) as unknown and skips the
low-memory prompt instead of misreading it as low memory.
* Move logger and key signals from libcockatrice_utility to Cockatrice.
Took 9 minutes
* Only link Qt::Core instead of COCKATRICE_QT_MODULES to libraries, if possible.
Took 2 minutes
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Co-authored-by: Lukas Brübach <Bruebach.Lukas@bdosecurity.de>