Add STL compatibility checks

[adamfowleruk]

Please start with a use case description for a USER of this enhancement

[Who] As an application developer

[What] I need to use Herald classes with or instead of C++ STL classes in a compatible way, interchangeably

[Value] In order to achieve the principle of least astonishment to the use of the Herald API (thus saving me time during development)

Describe the potential solution you'd like

A clear and concise description of what you want to happen within Herald.

• Ensure all datatypes are Move+CopyConstructable and Move+CopyAssignable
• Ensure containers are interchangeable with their STL equivalents they are replacing

Describe alternatives you've considered

A clear and concise description of any alternative solutions or features you've considered.

Considered leaving the API's compatibility as best efforts or as needed, but this is likely to introduce inconsistency to the API, to cause bugs, and to make the Herald C++ API hard to consume.

Additional context

Add any other context or screenshots about the feature request here.

• CopyConstructible reference: https://en.cppreference.com/w/cpp/named_req/CopyConstructible
• CopyAssignable reference: https://en.cppreference.com/w/cpp/named_req/CopyAssignable
• Container requirements reference: https://en.cppreference.com/w/cpp/named_req/Container

Relative priority

Please give an indication of a relative priority for this enhancement.

Ensures correct function of internal core classes, and so tests for this are considered high priority.