Add context diagram and cable tree for PhysicalPort

With issue #161 we identified that `.context_diagram` (displaying) just the context of a `PhysicalPort` and `cable_tree` displaying both sides of the trees together is needed beside the scoping described in the issue.

This issue is solved when:

- [x] `context_diagram` is added to `PhysicalPort`
- [ ] `cable_tree` is added to `PhysicalPort` 