[Chore] Separate IR into its own crate

[wingertge]

Moves IR to a separate crate and moves some types around to more cleanly separate it from the runtime types like bindings.
Makes IR types implement Hash and Eq so they can be put into hash based collections like HashSet or HashMap. This is especially useful for Variable. To do this, a manual override is used for ConstantScalarValue::Float and the scope.
Adds optional bitcode serialization so we have more flexibility for the upcoming kernel cache.