URI Expansion on attributes for String Filters

[kzangeli]

String Filters in ngsild need to URI expand the attribute.
E.g. for the string filter ?q=A1.i==12 A1 will be URI expanded to http:/xxx.yyy.zzz/A1 (or any other URI depending on the @context).

But, what happens if an attribute is created with APIv2?
Then its name is actually "A1" in the database and after URI expansion, A1 will not be found.
To fix this, we'd need to know that en entity/attribute has been created with APIv2 and not ngsild and no URI expansion should be done for this entity/attribute.