⛰️[EPIC]: Distributed GNN Example

[mnabian]

### Example development
- [ ] https://github.com/NVIDIA/modulus/issues/358
- [ ] Verify the model produces accurate results

### Distributed computing
- [ ] Enable distributed GNNs on single-level mesh
- [ ] Enable distributed GNNs on multi-level mesh
- [ ] Enable distributed I/O

### Documentation
- [ ] Add README