feat(multithreading): Prevent use of thread-safe (locked) functions inside the server

This gives a warn if a function is used that can potentially lead to a
deadlock.

src/server/ua_server_internal.h

@@ -28,6 +28,11 @@
 
 _UA_BEGIN_DECLS
 
+#if UA_MULTITHREADING >= 100
+#undef UA_THREADSAFE
+#define UA_THREADSAFE UA_DEPRECATED
+#endif
+
 #ifdef UA_ENABLE_PUBSUB
 #include "ua_pubsub_manager.h"
 #endif