Spike: Support Apple M1 in Qt 5.15

Today ARM hardware architectures are supported in Qt 6.2 so that Qt Creator can be downloaded and installed and Qt applications developed also on newer Mac M1 chipsets and not only on older Intel-based  Mac hardware.

Many customers have requested similar support for Qt 5.15 where the developer today either has to use Rosetta2 for running Qt Creator or has to build Qt and Creator from source code.

This ticket tracks the investigation of what is needed on to bring M1 support also to Qt 5.15.

There are two aspects to the M1 compatibility, Qt Creator and Qt libraries. Here it is enough that only Qt libraries are ARM compatible while Qt Creator can be run in Rosetta2. One consideration is all the dependencies that Qt has, since also those need to be ARM-compatible and in TQC CI many dependent libraries need to be made ARM-compatible in 5.15 also.

It is also ok if some modules are left outside of the support, prime candidate being Web Engine. These can be handled with PS support as needed.