Check that assignment to parameters in function calls are null-safe.

For example, it is unsafe to pass a nullable value as a nonnull parameter.
```
void foo(int * _Nonnull x);
int * _Nullable x = ...;
foo(x); // Unsafe
```

PiperOrigin-RevId: 468782730
diff --git a/nullability_verification/BUILD b/nullability_verification/BUILD
index d98a9b1..9ff987c 100644
--- a/nullability_verification/BUILD
+++ b/nullability_verification/BUILD
@@ -36,6 +36,7 @@
         "@llvm-project//clang:analysis",
         "@llvm-project//clang:ast",
         "@llvm-project//clang:ast_matchers",
+        "@llvm-project//clang:basic",
         "@llvm-project//llvm:Support",
     ],
 )