Add Param

[douglaswsilva]

• Add set and get params to wrapper.

[JonasVautherin]

When building with latest develop, I get errors such as the following:

backend/src/mission/mission.grpc.pb.h:244:11: error: ‘class dronecode_sdk::rpc::mission::MissionService::Stub::experimental_async’ has pointer data members [-Werror=effc++]
     class experimental_async final :
           ^~~~~~~~~~~~~~~~~~
backend/src/mission/mission.grpc.pb.h:244:11: error:   but does not override ‘dronecode_sdk::rpc::mission::MissionService::Stub::experimental_async(const dronecode_sdk::rpc::mission::MissionService::Stub::experimental_async&)’ [-Werror=effc++]
backend/src/mission/mission.grpc.pb.h:244:11: error:   or ‘operator=(const dronecode_sdk::rpc::mission::MissionService::Stub::experimental_async&)’ [-Werror=effc++]
cc1plus: all warnings being treated as errors

I need to figure out what's happening there, sorry for the delay 😕.

[julianoes]

Many many changes 😄

[JonasVautherin]

Thanks a lot @douglaswsilva!