cubicweb-medicalexp #3911759 Add Survival data [validation pending]

Add Survival data etype with relapse date info, ...

prioritynormal
typebug
done in0.11.0
load0.200
load left0.000
closed by#8d4d2f706446 [schema] Add SurvivalData, closes #3911759
patch[schema] Add SurvivalData, closes #3911759 [applied]