[clang-format] Parse nullability attributes as a pointer qualifier

Before:
void f() { MACRO(A * _Nonnull a); }
void f() { MACRO(A * _Nullable a); }
void f() { MACRO(A * _Null_unspecified a); }

After:
void f() { MACRO(A *_Nonnull a); }
void f() { MACRO(A *_Nullable a); }
void f() { MACRO(A *_Null_unspecified a); }

Reviewed By: JakeMerdichAMD

Differential Revision: https://reviews.llvm.org/D86713