add physics server loopback (both client and server in the same process, using shared memory)

add physics server direct (client and server in the same process, directly processing commands without shared memory transport mechanism)

examples/SharedMemory/PhysicsDirectC_API.h

@@ -0,0 +1,19 @@
+#ifndef PHYSICS_DIRECT_C_API_H
+#define PHYSICS_DIRECT_C_API_H
+
+#include "PhysicsClientC_API.h"
+
+#ifdef __cplusplus
+extern "C" { 
+#endif
+
+
+///think more about naming. Directly execute commands without transport (no shared memory, UDP, socket, grpc etc)
+b3PhysicsClientHandle b3ConnectPhysicsDirect();
+
+    
+#ifdef __cplusplus
+}
+#endif
+
+#endif //PHYSICS_DIRECT_C_API_H