Add saving of diagnostic messages information

Add saving of diagnostic messages information

Add saving of diagnostic messages receive state, last value,
and timestamp associated to it.
Add methods to get/set these information.
Add initialisation for added atributes.
Add boolean to set receive state at initialisation.
Generate all 'diagnostic-message.cpp' containing diagnostic messages
to add receive state initialisation.

Bug-AGL: SPEC-1347

Change-Id: Iee82ca3b5f79fd267717ae074d5456b8cbc1c377
Signed-off-by: Jonathan Aillet <jonathan.aillet@iot.bzh>