Add Variant `in` operator for any String/StringName operands

Allow using String or StringName types as operand in any position of the
`in` operator, which is more convenient in scripting when interacting
with data in the engine (such as a Node name).

core/variant/variant_op.cpp

@@ -641,7 +641,10 @@ void Variant::_register_variant_operators() {
 	register_op<OperatorEvaluatorNotFloat>(Variant::OP_NOT, Variant::FLOAT, Variant::NIL);
 	register_op<OperatorEvaluatorNotObject>(Variant::OP_NOT, Variant::OBJECT, Variant::NIL);
 
-	register_op<OperatorEvaluatorInStringFind>(Variant::OP_IN, Variant::STRING, Variant::STRING);
+	register_op<OperatorEvaluatorInStringFind<String>>(Variant::OP_IN, Variant::STRING, Variant::STRING);
+	register_op<OperatorEvaluatorInStringFind<StringName>>(Variant::OP_IN, Variant::STRING_NAME, Variant::STRING);
+	register_op<OperatorEvaluatorInStringNameFind<String>>(Variant::OP_IN, Variant::STRING, Variant::STRING_NAME);
+	register_op<OperatorEvaluatorInStringNameFind<StringName>>(Variant::OP_IN, Variant::STRING_NAME, Variant::STRING_NAME);
 
 	register_op<OperatorEvaluatorInDictionaryHasNil>(Variant::OP_IN, Variant::NIL, Variant::DICTIONARY);
 	register_op<OperatorEvaluatorInDictionaryHas<bool>>(Variant::OP_IN, Variant::BOOL, Variant::DICTIONARY);

core/variant/variant_op.h

@@ -1213,22 +1213,44 @@ public:
 
 ////
 
+template <class Left>
 class OperatorEvaluatorInStringFind {
 public:
 	static void evaluate(const Variant &p_left, const Variant &p_right, Variant *r_ret, bool &r_valid) {
-		const String &str_a = *VariantGetInternalPtr<String>::get_ptr(&p_left);
+		const Left &str_a = *VariantGetInternalPtr<Left>::get_ptr(&p_left);
 		const String &str_b = *VariantGetInternalPtr<String>::get_ptr(&p_right);
 
 		*r_ret = str_b.find(str_a) != -1;
 		r_valid = true;
 	}
 	static inline void validated_evaluate(const Variant *left, const Variant *right, Variant *r_ret) {
-		const String &str_a = *VariantGetInternalPtr<String>::get_ptr(left);
+		const Left &str_a = *VariantGetInternalPtr<Left>::get_ptr(left);
 		const String &str_b = *VariantGetInternalPtr<String>::get_ptr(right);
 		*VariantGetInternalPtr<bool>::get_ptr(r_ret) = str_b.find(str_a) != -1;
 	}
 	static void ptr_evaluate(const void *left, const void *right, void *r_ret) {
-		PtrToArg<bool>::encode(PtrToArg<String>::convert(right).find(PtrToArg<String>::convert(left)) != -1, r_ret);
+		PtrToArg<bool>::encode(PtrToArg<String>::convert(right).find(PtrToArg<Left>::convert(left)) != -1, r_ret);
+	}
+	static Variant::Type get_return_type() { return Variant::BOOL; }
+};
+
+template <class Left>
+class OperatorEvaluatorInStringNameFind {
+public:
+	static void evaluate(const Variant &p_left, const Variant &p_right, Variant *r_ret, bool &r_valid) {
+		const Left &str_a = *VariantGetInternalPtr<Left>::get_ptr(&p_left);
+		const String str_b = VariantGetInternalPtr<StringName>::get_ptr(&p_right)->operator String();
+
+		*r_ret = str_b.find(str_a) != -1;
+		r_valid = true;
+	}
+	static inline void validated_evaluate(const Variant *left, const Variant *right, Variant *r_ret) {
+		const Left &str_a = *VariantGetInternalPtr<Left>::get_ptr(left);
+		const String str_b = VariantGetInternalPtr<StringName>::get_ptr(right)->operator String();
+		*VariantGetInternalPtr<bool>::get_ptr(r_ret) = str_b.find(str_a) != -1;
+	}
+	static void ptr_evaluate(const void *left, const void *right, void *r_ret) {
+		PtrToArg<bool>::encode(PtrToArg<StringName>::convert(right).operator String().find(PtrToArg<Left>::convert(left)) != -1, r_ret);
 	}
 	static Variant::Type get_return_type() { return Variant::BOOL; }
 };