review some DataHolder methods signatures to use ValueContext:

• ValueContext has the status info, available for has/get/set/removeValue
• Another context should have the allowMultiValuedPathSegments boolean, for has/getValue. The hasValue methods aren't using it for the moment but it could be nice. And we could use this boolean for externalizable value too, because it's not the case for now
• Another context should have a boolean to take empty value or not in hasValue methods
• Another context should manage the default values for getValue methods. Doing this, we could use default to get externalizable values

Some of the existent method could be removed (like getValue with allowMultiValuedPathSegments boolean), but some very useful methods should be kept to keep the API use simple