Allow vectorial min max settings for Node Groups' Vector sockets

Currently, Node Groups' Vector-type sockets allow for vectorial default values, but their minimum and maximum settings are not vectors but single values meant to equally affect all vector's components. I'd rather they are vectors, too.

Not just for consistency's sake but because I'm meeting some cases (game shaders that encode disparate properties as vectors for efficiency's sake) where I have to deal with limits the likes of (0,0,-1,0) to (1,1,1,3).

As it is right now, I'm having to separate those vectors sockets into their components to be able to set proper limits to each, with the overhead in panel real estate, node group plumbing, and even add-on code needed to deal with that.