GoFSH creating `^` rules against the wrong constraints about gofsh

[cmoesel]

One issue I think we're running into is that constraint.source is automatically set by SUSHI when creating a constraint (here). Basically it always ends up being the URL of the SD where the constraint is created.

But, even though SUSHI automatically creates it, we're not marking it as a processed path in GoFSH. So GoFSH will always create a caret rule for it. So first thing to do is mark it as processed when appropriate.

[cmoesel]

But I think this issue still exists if there is anything weird in the constraint, like an extension. In that case, GoFSH would have to create a ^ rule, and using the current algorithm would probably still pick the wrong index number.