Move the scalar type serializers to a separated translation units. This
make code more readable. Adjust constraints to follow common project
coding standards and make constrains compilation faster. Make complex
functions out-of-line to avoid unwanted binary expansion.
Pick-to: 6.8 6.9
Task-number: QTBUG-128812
Change-Id: Ib5311f392e32e5f31416448d2f306ae91155f873
Reviewed-by: Dennis Oberst <dennis.oberst@qt.io>