Add enum name to default case deserialization exception for C++

[cconverse711]

Description

Includes enumeration name in std::runtime_error message for enum deserialization failure.

Related Issue

#2796

Motivation and Context

#2796

Previous Behaviour / Output

std::runtime_error is raised with message Input JSON does not conform to schema!

New Behaviour / Output

std::runtime_error raised with message like Cannot deserialize to enumeration "FooBar".

How Has This Been Tested?

Existing C++ unit tests

Screenshots (if appropriate):