AK: Allow NonnullRefPtr::ptr() when in "unknown" typestate.

Clang loses the typestate when passing NonnullRefPtr's via lambda captures.
This is unfortunate, but not much we can do about it. Allowing ptr() makes
it possible to use captured NonnullRefPtrs as you'd expect.

AK/NonnullRefPtr.h

@@ -148,13 +148,13 @@ public:
         return *leakedPtr;
     }
 
-    CALLABLE_WHEN(unconsumed)
+    CALLABLE_WHEN("unconsumed","unknown")
     T* ptr()
     {
         ASSERT(m_ptr);
         return m_ptr;
     }
-    CALLABLE_WHEN(unconsumed)
+    CALLABLE_WHEN("unconsumed","unknown")
     const T* ptr() const
     {
         ASSERT(m_ptr);