9.1 Add `FixtureFactory::createNodeOfType` for unit tests.

[mhsdesign]

we were discussing how to stub nodes in tests https://neos-project.slack.com/archives/C3MCBK6S2/p1686294507655429

and it was noted that we need some kind of factory for this:

if the input for the test is a Node, I'd just instantiate one, if the output that is to be tested is a node, then use commands in behat

imho the CR should provide something like FixtureFactory::createNodeOfType for unit tests, then you don't have to deal with that in every test