Add ES 320 support and additional error checks for SPV_NV_mesh_shader

- Add ES 320 support
- Error out use of perprimitiveNV for non mesh/fragment shaders
- Error out use of mesh/task shaders w/o use of NV_mesh_shader
- Error out use of NV_mesh_shader for non task/mesh shaders
- Error out use of perviewNV for non mesh shaders
- Error out use of taskNV for non mesh/task shaders
- Add test case for mesh shader with ES 320 profile

glslang/MachineIndependent/preprocessor/Pp.cpp

@@ -874,6 +874,11 @@ int TPpContext::CPPextension(TPpToken* ppToken)
         return token;
     }
 
+#ifdef NV_EXTENSIONS
+    if (!parseContext.validateExtensionName(ppToken->loc, extensionName))
+        return token;
+#endif
+
     parseContext.updateExtensionBehavior(line, extensionName, ppToken->name);
     parseContext.notifyExtensionDirective(line, extensionName, ppToken->name);