[netatmo] Compatibility with OpenHAB 3 (Update to newer Swagger version and code...

[netatmo] Compatibility with OpenHAB 3 (Update to newer Swagger version and code generation libraries replaced) (#8274) (#8652)

Swagger upgrade for the Netatmo binding (required to use the OAS 3 Swagger annotations, the old annotations dependencies were removed with OpenHAB 3)
- Swagger-Codegen updated to the latest version (to generate the OAS 3 Swagger annotations)
- Retrofit replaced by the default code generation (Retrofit 1 code generation is broken with newer swagger-codegen versions and an update to Retrofit 2 is also incompatible and would require more dependencies)
- NULL handling for collections introduced (newer versions of the Swagger codegen return NULL for empty collections instead of an empty collection ...)
- The binding is now working completely again (compiles and starts), but there are still some TODOs

Signed-off-by: Sven Strohschein <sven.strohschein@gmail.com>
sven.strohschein@gmail.com>