Add GCN and FiLM jit example

[ftxj]

This PR wants to make example/film.py and example/gcn.py jittable. In the original implementation, if we just add .jittable() modify and call the torch.jit.script(model) function, we will get some errors. In example/gcn.py, the error msg is Expected a proper Tensor but got None, and in example/film.py, we will get a runtime error: object has no attribute or method '__call__'.

So, we use some small modifications to make these examples really jittable. In the example/film.py, since TorchScript doesn't support the index loop of ModuleList, we split the the last conv layer. In the example/gcn.py, we add a type hint for edge_weight variable. And we kept everything else the same.