### Godot version

v4.0.rc1.official [8843d9ad3]

### System information

Lubuntu

### Issue description

You can't use + or += to mutate typed arrays.

It seems to be not correctly getting the type information from the second operand.

An erudite poster on the discord puts it differently:
> it's more like operator + doesn't retain Array typing
> the syntax for Array Concatenation via operators, but the idea gets across i think


The error you see is:
```Trying to assign an array of type "Array" to a variable of type "Array[int]".```


### Steps to reproduce

```
	var Alice: Array[int] = [1,2,3]
	var Bob: Array[int] = [4,5,6]
	Alice += Bob
```
This will crash with the above error message.

### Minimal reproduction project

[plus_syntax_broken_demo_project.zip](https://github.com/godotengine/godot/files/10694514/plus_syntax_broken_demo_project.zip)

if (member.variable->setter->parameters.size() > 0) {
						member.variable->setter->parameters[0]->datatype_specifier = member.variable->datatype_specifier;
						member.variable->setter->parameters[0]->set_datatype(member.get_datatype());
					}
					resolve_function_body(member.variable->setter);
				}
			}
		} else if (member.type == GDScriptParser::ClassNode::Member::GROUP) {
			
			resolve_annotation(member.annotation);
			member.annotation->apply(parser, nullptr);
		}
	}
	
	for (int i = 0; i < p_class->members.size(); i++) {
		GDScriptParser::ClassNode::Member member = p_class->members[i];
		if (member.type == GDScriptParser::ClassNode::Member::VARIABLE) {
#ifdef DEBUG_ENABLED
			HashSet<GDScriptWarning::Code> previously_ignored_warnings = parser->ignored_warnings;
			for (GDScriptWarning::Code ignored_warning : member.variable->ignored_warnings) {
				parser->ignored_warnings.insert(ignored_warning);
			}
			if (member.variable->usages == 0 && String(member.variable->identifier->name).begins_with("_")) {
				parser->push_warning(member.variable->identifier, GDScriptWarning::UNUSED_PRIVATE_CLASS_VARIABLE, member.variable->identifier->name);
			}
#endif
			if (member.variable->property == GDScriptParser::VariableNode::PROP_SETGET) {
				GDScriptParser::FunctionNode *getter_function = nullptr;
				GDScriptParser::FunctionNode *setter_function = nullptr;
				bool has_valid_getter = false;