[REF] Code readability changes on activity tokens.

[REF] Code readability changes on activity tokens.

I've been trying to get to grips with this code and this addresses 2 things I found very confusing - notably

- using activityId when we were referring to a fieldname - we use a combination of  &  for
variables but normally when it's closely related to a query we use activity_id
- the function name getEntityContextSchema() was unclear to me - I concluded that in fact we were retrieving
the nname of the field for the entity ID