Draft: Differentiate variable types in pyg data by adding prefix to each variable name

• Add hit_ prefix to all hit like variables
• Add track_ prefix to all track like variables
• Add edge_ prefix to all edge like variables
• Change accordingly in module map
• Change accordingly in GNN stage
• Change accordingly in track building stage
• Change accordingly in metric learning stage
• Change accordingly in filter stage
• Modify all functions that currently use array size to determine variable types
• Update all config files
• Test with ttbar events
• Test with single-particle events
• Test with examples
• Pass pipeline