Add generic types for useVueFlow

[mdominiak2]

I would like to type the Nodes. I haven't found a way to do this, so I propose generic types for useVueFlow.
Something like this useVueFlow<NodaData, EdgeData, CustomEvents, KeyType>.

[bcakmakoglu]

Mh... yeah I've thought about that too but then decided not to go that route atm.
You can still type nodes yourself though as they allow for generics, like const nodes = ref<Node<NodeData, CustomEvents>[]>([...])

[bcakmakoglu]

Might be I'll add this generic in 2.0.0 but I'm not sure yet 🤷‍♂️