QTlsBackend is a factory itself - it creates TLS/X509 objects. Having
an intermediary between Factory->Backend->TLS primitive does not look
very natural thus let's squash the first two parts. Backend is a factory
creating TLS primitives, but its static functions also provide information
about backends availablei and give access to those backends.
Fixes: QTBUG-90606
Task-number: QTBUG-65922
Change-Id: I8409d81fd11fb46e6ab4465b4937a7680a8c2447
Reviewed-by: Alex Blasche <alexander.blasche@qt.io>
Reviewed-by: Mårten Nordheim <marten.nordheim@qt.io>
1a2dd92767