(Codegen) Add warning when the target folder for code generation is in a different project

[antoine-morvan]

The scenario editor allows the generated code to be generated in a different Eclipse project than the one containing the scenario. This can lead to trouble locating the generated code, especially when working on several versions on the same project, or simply when copying scenarios.

Solution could be to output a warning / info in the log when this occurs.

[leos313]

or, maybe better, a little window with "choose output folder" with the default value of "<current_project>/Code/generated". Users need just to press "Next"