FromNodes are not correctly shared in executable model

Utility class FunctionUtils generates generic FunctionN starting from functions with fixed arity, but doing so the fingerprint of the original function gets lost, thus preventing correct comparison of lambdas and sharing of nodes containing them. The effect of this is visible for instance in FromTest.testFromSharingWithAccumulate since when running it with executable model there is no node sharing as expected (modify the test to check for actual node sharing and make it fail otherwise).