vsdg: node instantiation helper
vsdg: node instantiation helper

Add a helper function to instantiate a node that uses the type signature
represented within the operation itself.

Signed-off-by: Nico Reißmann <d8255cca0642bdc1e6f9b45da9cb618d308e389b@gmail.com>

phate/jive,phate/jive,phate/jive