refactor: Op traits

[alexander-camuto]

Op notation has started to become overloaded and we need to split ops into multiple files. To help with this we create a generic Op trait that is common to all implemented operations.

This PR reconfigures the circuit module to use this trait.

should also:

• deprecate theOpKind enum in the graph module
• move towards using traits in function calls.

Bonuses:

• starts to implement instance_norm
• fix: thanks to @Mickanos for flagging that the neg doesn't constraint with NEG selector
• creates a dummy layout pass for more accurately estimating the num of rows needed (rather than having to calculate those values by hand)
• reduces model configuration to a single config.