Type-C: Convert `examples/std/bin/type_c/unconstrained.rs` into an integration test

[RobertZ2011]

Create an integration test that covers the unconstrained behavior of the type-c service implementation.

• A single unconstrained type-C PSUs should unconstrain other ports
• Multiple unconstrained type-C PSUs should unconstrain all ports
• A single unconstrained non-type-C should unconstrain all ports