Add `Host`/`HostInterface` to C++

[foundrytom]

What

The mirror of Manager/ManagerInterface for the host representation.

ACs

• Host class in the managerAPI C++ namespace.
• HostInterface class in the hostAPI C++ namespace (incl. HostInterfacePtr).
• Support for:
  • identifier
  • displayName
  • info
• Issue for C implementation, with any design notes.
• Python bindings as the base for existing Python Host/HostInterface classes
• Existing test_host.py tests used for coverage
  • Additions for the handling of edge cases where invalid values are supplied to constructors/etc.

Out of scope

• _interface
• loggin/audit

[feltech]

Added C API issue as #423. Nothing jumped out as particularly onerous during development in #422.