allow dynamic resolving within the graph

[PythonFZ]

Introduce dynamic graph building

graph = znflow.DiGraph()
with graph:
    node1 = AddOne(inputs=1)
    for _ in range(10):
        node1 = AddOne(inputs=node1.outputs)
        if znflow.resolve(node1.outputs) > 5:
            break

In the current version, there is no flexibility in choosing the deployment version.