[analyzer] Do not report NSError null dereference for _Nonnull params.
We want to trust user type annotations and stop assuming pointers declared
as _Nonnull still can be null. This functionality is implemented as part
of NullabilityChecker as it already tracks non-null types.
Patch by Valeriy Savchenko!
Differential Revision: https://reviews.llvm.org/D77722