Use OpenGL 3.3 core profile instead of compatibility profile

- Rename OpenGL to GLES3 in the source code per community feedback.
  - The renderer is still exposed as "OpenGL 3" to the user.
- Hide renderer selection dropdown until OpenGL support is more mature.
  - The renderer can still be changed in the Project Settings or using
    the `--rendering-driver opengl` command line argument.
- Remove commented out exporter code.
- Remove some OpenGL/DisplayServer-related debugging prints.

platform/linuxbsd/gl_manager_x11.h

@@ -33,9 +33,9 @@
 
 #ifdef X11_ENABLED
 
-#include "drivers/opengl/rasterizer_platforms.h"
+#include "drivers/gles3/rasterizer_platforms.h"
 
-#ifdef OPENGL_ENABLED
+#ifdef GLES3_ENABLED
 
 #include "core/os/os.h"
 #include "core/templates/local_vector.h"
@@ -124,7 +124,7 @@ public:
 	~GLManager_X11();
 };
 
-#endif // OPENGL_ENABLED
+#endif // GLES3_ENABLED
 #endif // X11_ENABLED
 
 #endif // GL_MANAGER_X11_H