[IRGen] Fix witness table miscompilation.
[IRGen] Fix witness table miscompilation.

If a foreign type conforms to a protocol, and that conformance is not
resilient, we were emitting an instantantiation function but it would
never be called because we weren't emitting the `GenericWitnessTable`
that would have contained a reference to it.

This was happening because of a missing `isSynthesizedNonUnique()` call
in `isDependentConformance()`.

rdar://97290618

roambotics/swift,roambotics/swift,glessard/swift,roambotics/swift,glessard/swift,glessard/swift,glessard/swift,apple/swift,roambotics/swift,apple/swift,benlangmuir/swift,apple/swift,glessard/swift,glessard/swift,apple/swift,benlangmuir/swift,roambotics/swift,apple/swift,benlangmuir/swift,roambotics/swift,benlangmuir/swift,benlangmuir/swift,benlangmuir/swift,apple/swift