Feature Request: Use `u64` for Token-Group Interface `max_size`

[jacksondoherty]

Although they don't exist today, there are conceivable NFT projects that could have billions of members, especially with compression. For example, a project I'm working on called Garden will have a total possible supply of ~64B, which doesn't fit in u32. Unless there is a significant benefit to using u32 that I'm not aware of, we should use the maximum type here.