Add tag types for Ort::Float16_t and Ort:Bfloat16_t structs (#5716)
Add tag types for Ort::Float16_t and Ort:Bfloat16_t structs
that contain uint16_t values for float16 and bfloat16.
These will serve as type dispatching types for C++ API.
They are of uint16_t size and arrays of these types can be used
to create Tensors of the corresponding types.
Make documentation Doxygen compliant.