Support static methods in C# bindings generator

modules/mono/editor/bindings_generator.h

@@ -136,6 +136,11 @@ class BindingsGenerator {
 		 */
 		bool is_vararg = false;
 
+		/**
+		 * Determines if the method is static.
+		 */
+		bool is_static = false;
+
 		/**
 		 * Virtual methods ("virtual" as defined by the Godot API) are methods that by default do nothing,
 		 * but can be overridden by the user to add custom functionality.