Fix EditorPlugin::forward_spatial_input_event in GDScripts addons

tools/editor/editor_plugin.cpp

@@ -27,6 +27,7 @@
 /* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.                */
 /*************************************************************************/
 #include "editor_plugin.h"
+#include "scene/3d/camera.h"
 #include "plugins/canvas_item_editor_plugin.h"
 #include "plugins/spatial_editor_plugin.h"
 #include "tools/editor/editor_node.h"