Generalized handling of `meta` object

[maurei]

Currently the OpenApi integration only assumes a meta object at the top-level of a response document.

In JADNC it is possible to include metadata at places deeper in the document structure as well. The following places can be used to configure metadata:

• JsonApiOptions.IncludeTotalResourceCount
• Implementations of IResponseMeta
• Implementations of ResourceDefinitions.GetMeta(TResource)

Upon adding meta to schemas during the generation, these configurations should be taken into account.

[bkoelman]

Should review all places in the JSON:API spec where meta can occur, and possibly update JADNC accordingly. Then review the OpenAPI models, including atomic operations.