Add explicit support for graph-structured data

[dtchang]

Please add explicit support for graph-structured data including

• quantum graph kernels
• quantum graph neural networks, particularly quantum graph convolutional networks

[dtchang]

Do you have plans for this? If so, what is the time frame? In any case, for quantum graph kernels, can you suggest what encoding circuits (implemented, new) to use? and what references to look into? Thanks.