Add option to include the python module name

[s-knibbs]

To aid code generation when generating python code from the schemas within an OpenAPI spec, it would be useful to have an option to include the module name with each schema:

@dataclass
class Pet(JsonSchemaMixin):
    """A pet"""
    name: str
    age: int

>>> JsonSchemaMixin.all_json_schemas(schema_type=SchemaType.SWAGGER_V3, include_module_names=True)
{
    "Pet": {
        "description": "A pet",
        "type": "object",
        "x-module-name": "petstore.data_types",
        ....
    }
}