[Core] Add LocalVector::has for convenience

Author: AThousandShips

include/godot_cpp/templates/local_vector.hpp

@@ -257,6 +257,10 @@ class LocalVector {
 		return -1;
 	}
 
+	bool has(const T &p_val) const {
+		return find(p_val) != -1;
+	}
+
 	template <typename C>
 	void sort_custom() {
 		U len = count;