Make hanger settings compatible with stacked fabrication buttons

currently the settings only see the 'button name' and not the items stacked within this.

1) if the service button has constraints built into them, the evolve hanger spec should be able to be set to the stacked button but follow the constraints for what hanger on the button it inserts. in theory, the hangers spacing would follow the 'evolve' settings, but the specific hanger selection would follow the service button constraints. currently, it inserts the 1st item on the stacked button, regardless of the constraint. i.e. a button stack that has a copper loop hanger (up to 2" pipe) and then a clevis for > 2"...through evolve it puts the copper loop on everything.

2) if the service button DOESN'T have constraints, the user should be able to not just point to the 'button' but to the specific item within the button. as it currently is, just like on the 'constrained' button it only inserts the 1st item on the stack, which isn't always the desired item.

the only way to get at the right hang