AK: Add ErrorOr<T>::release_value_but_fixme_should_propagate_errors()

This is an alternative to ErrorOr<T>::release_value() that can be used
when converting code to signal that we're releasing the value without
error propagation as a way to move forward now.

This makes these cases much easier to find later on, once more paths for
error propagation are available.

AK/Error.h

@@ -78,6 +78,8 @@ public:
     T release_value() { return m_value.release_value(); }
     Error release_error() { return m_error.release_value(); }
 
+    T release_value_but_fixme_should_propagate_errors() { return release_value(); }
+
 private:
     Optional<T> m_value;
     Optional<Error> m_error;