### 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)

variable_type = return_type;
				variable_type.type_source = list_type.type_source;
			} else if (!list_type.is_hard_type()) {
				variable_type.kind = GDScriptParser::DataType::VARIANT;
			} else {
				push_error(vformat(R"(Unable to iterate on object of type "%s".)", list_type.to_string()), p_for->list);
			}
		} else if (list_type.builtin_type == Variant::ARRAY || list_type.builtin_type == Variant::DICTIONARY || !list_type.is_hard_type()) {
			variable_type.kind = GDScriptParser::DataType::VARIANT;
		} else {
			push_error(vformat(R"(Unable to iterate on value of type "%s".)", list_type.to_string()), p_for->list);
		}
	}
	if (p_for->variable) {
		p_for->variable->set_datatype(variable_type);
	}
	resolve_suite(p_for->loop);
	p_for->set_datatype(p_for->loop->get_datatype());
#ifdef DEBUG_ENABLED
	if (p_for->variable) {
		is_shadowing(p_for->variable, R"("for" iterator variable)");
	}
#endif
}
void GDScriptAnalyzer::resolve_while(GDScriptParser::WhileNode *p_while) {
	resolve_node(p_while->condition, false);
	resolve_suite(p_while->loop);
	p_while->set_datatype(p_while->loop->get_datatype());
}
void GDScriptAnalyzer::resolve_assert(GDScriptParser::AssertNode *p_assert) {