[feat] /configuration implementation

[lgrd]

Need

/configuration route is not implemented in the administration API. This route allow an administrator to get the configuration of road2 administrator and to modify it.

Tasks

• Delete onStart feature. See [del] onStart option and feature #48
• Allow verification and creation of an administrator without any services. See [feat] init admin without services #51
• Allow verification and creation and publication of a service without any resources and/or sources. See feat(init): no stop of service if source or resource dir is empty #47
• Code GET /configuration. See [feat] compute GET /configuration #59
• Code PATCH /configuration. See [feat] Compute /PATCH configuration #104
• Update doc (ex. functionalities, changelog)
• Update tests (new classes if there are; rtest for this route)
• Run tests inside docker (rtest, ctest, utest, itest)