Fix CanonicalFactoryTrait::factoryCreate return type should be static

[acbramley]

CanonicalFactoryTrait::factoryCreate has a return type of :self but is designed to be used in other classes.
This causes issues with phpstan such as

Method PreviousNext\Ds\Common\Layout\Section\Section::create() should return static(PreviousNext\Ds\Common\Layout\Section\Section) but returns PreviousNext\Ds\Common\Layout\Section\Section

[dpi]

Are you able to DM me a reference to the code where this is used?

You are calling only from the root class right? Common::factoryCreate never Downstream::factoryCreate?

And ensuring the constructor is final in common, or not overridden downstream, so signature (params/return) cant vary downstream