Turn name restriction into proper Search API processor

Problem

The Social Profile Privacy allows hiding of real names in search for users that have a nickname filled in. This is currently implemented using some quite complex query conditions. This leads to some edge cases where this malfunctions.

Solution

Re-implement as a Search API processor. This allows us to create a field that contains the value for restricted users and allows the value for unrestricted users to live next to it. In the query alter we can then simply disable fields the user does not have access to. This creates a more robust solution.