[ObjC][CodeGen] Fix missing debug info in situations where an instance and...

[ObjC][CodeGen] Fix missing debug info in situations where an instance and class property have the same identifier

Since the introduction of class properties in Objective-C it is possible to declare a class and an instance
property with the same identifier in an interface/protocol.

Right now Clang just generates debug information for whatever property comes first in the source file.
The second property is ignored as it's filtered out by the set of already emitted properties (which is just
using the identifier of the property to check for equivalence).  I don't think generating debug info in this case
was never supported as the identifier filter is in place since 7123bca7
(which precedes the introduction of class properties).

This patch expands the filter to take in account identifier + whether the property is class/instance. This
ensures that both properties are emitted in this special situation.

Reviewed By: aprantl

Differential Revision: https://reviews.llvm.org/D99512