Topology ports semantics

[Kronos3]

This PR implements topology port semantics according to the spec from #748

Interesting Changes

• Topology uses and component instance uses were merged into a single interfaceInstanceUse
• The component's portMap + specialPortMap were moved out into a separate PortInterface construct so that it could be reused inside topology
• A new port instance case class was added PortInstance.Topology for wrapping ports with a new name to impement topology ports.
• SpecLoc.Instance (was for component instance) and SpecLoc.Topology was merged into SpecLoc.Instance (interface instance). (This required a spec update).

Closes #745

[bocchino]

Why do we need to override equals here? What happens if we use the default equals?

[Kronos3]

This is required because we need a slightly more permissive == compared to default. This is so that we can compute port interfaces as sets of port instances. The default rule will also check the node.id which is not relevant for port instance but just for error reporting.

[bocchino]

That makes sense, thanks!

[bocchino]

I think what we are doing here is defining an equivalence relation that says that two port instance values are the same if they represent the same port instance in the context of a single interface. However, I'm a bit uncomfortable with the way the code is written -- it imposes a global equality relation to encode a relation that only makes sense locally. That could cause confusion in another context where we need or expect the true value equality relationship, and it's been overridden. Let's discuss offline.

[bocchino]

Looks great! I just have a few comments/questions about error messages and coding.