Expose individual components of UniquePortId in CXX API

## Brief feature description

The `UniquePortId` is made up of components:
```
pub struct UniqueSystemId {
pid: u32,
seconds: u32,
nanoseconds: u32,
counter: u32,
}
```

An API to access these individual elements, in addition to all of the bytes making up the ID, should be added.

Locate the CXX API definitions for UniquePortId and the UniqueSystemId representation described in the issue. First inspect how the ID's bytes are currently exposed, then identify the Rust/C++ boundary. Done means callers can read each listed component and the complete byte representation through the CXX API.

Written by the indexing model from the issue text.