Rename src/dst Nodes For Point Cloud Featurization

[melo-gonzo]

Would close the issue raised in #132 and #227. Renames the src_nodes and dst_nodes that are used for point cloud featurization to pc_src_nodes and pc_dst_nodes.

[laserkelvin]

I'm trying to grasp the connection between renaming the variables and how it addresses #132 and #227. Could you explain how the renaming impacts this?

[melo-gonzo]

@laserkelvin src_nodes and dst_nodes are added to the overall data sample in the dataset classes. these same src_nodes and dst_nodes are pulled out when constructing the graph, for example in the dgl conversion . your own comment here may clear it up for you.

[laserkelvin]

Pre-commit hooks are failing on test_dataset, can you address them?