AK: Mark Function as SWIFT_UNSAFE_REFERENCE

This allows us to import APIs that include a function without crashing
the frontend. Without this, it chokes on the move-only behavior of the
class.

AK/Function.h

@@ -35,6 +35,7 @@
 #include <AK/ScopeGuard.h>
 #include <AK/Span.h>
 #include <AK/StdLibExtras.h>
+#include <AK/Swift.h>
 #include <AK/TypeCasts.h>
 #include <AK/Types.h>
 
@@ -382,7 +383,7 @@ private:
     static constexpr size_t inline_capacity = 4 * sizeof(void*);
 
     alignas(inline_alignment) u8 m_storage[inline_capacity];
-};
+} SWIFT_UNSAFE_REFERENCE;
 
 }