* [BUG] [C++][Pistache] cpp-pistache-server generating API include undefined "Object.h" (#2769)
Should handle Object.h, AnyType.h correctly. Set.h also tested.
- #include Object.h removed and replaced by a typeMapping.put(object, nlohmann::json) like suggested in other issues
- object had an invalid syntax: ':' instead of '::' in types with namespace
- extra include of #include nlohmann/json.h removed when there's already #include <nlohmann/json.hpp>
- nlohmann::json is excluded from model namespace
Tested with custom petstore played, with suggested openapi specs coming from issues #2769, #10266, #14234
```bash
rm -rf samples/server/petstore/cpp-pistache-everything/ && ./bin/generate-samples.sh ./bin/configs/cpp-pistache-server-cpp-pistache-everything.yaml && cd samples/server/petstore/cpp-pistache-everything/ && mkdir build && cd build && cmake .. && cmake --build . --parallel
```
* - Adding to samples/server/petstore cpp-pistache-everything
* - .md and FILES missing
