Serialize tuple types from Node (#2405)

Summary:
bypass-github-export-checks

Pull Request resolved: https://github.com/pytorch/executorch/pull/2405

In https://github.com/pytorch/executorch/pull/2271, we already added
- IntList
- DoubleList
- BoolList
- ValueList

to the schema and the runtime's Value class. Their serialization was incomplete missing two components:
1. Receiving a list in `torch.fx.Node.args`.
2. Receiving a non-tensor in `torch.fx.Node`.

This change completes #2.

Also, we introduce a specific handler for `getitem` nodes as it is required. Every `function_call` outputting non-tensor `torch.fx.Node` is followed by a special `getitem` `function_call`.
ghstack-source-id: 218541429
exported-using-ghexport

Reviewed By: SS-JIA

Differential Revision: D54789099

fbshipit-source-id: 1e58cbc0246a8c651d95e9ef6707bacb60066e2b