### 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)

for (int i = 0; i < p_suite->statements.size(); i++) {
		GDScriptParser::Node *stmt = p_suite->statements[i];
		
		for (GDScriptParser::AnnotationNode *&E : stmt->annotations) {
			resolve_annotation(E);
			E->apply(parser, stmt);
		}
#ifdef DEBUG_ENABLED
		HashSet<GDScriptWarning::Code> previously_ignored_warnings = parser->ignored_warnings;
		for (GDScriptWarning::Code ignored_warning : stmt->ignored_warnings) {
			parser->ignored_warnings.insert(ignored_warning);
		}
#endif 
		resolve_node(stmt);
#ifdef DEBUG_ENABLED
		parser->ignored_warnings = previously_ignored_warnings;
#endif 
		decide_suite_type(p_suite, stmt);
	}
}
void GDScriptAnalyzer::resolve_assignable(GDScriptParser::AssignableNode *p_assignable, const char *p_kind) {
	GDScriptParser::DataType type;
	type.kind = GDScriptParser::DataType::VARIANT;
	bool is_constant = p_assignable->type == GDScriptParser::Node::CONSTANT;
	GDScriptParser::DataType specified_type;
	bool has_specified_type = p_assignable->datatype_specifier != nullptr;
	if (has_specified_type) {
		specified_type = type_from_metatype(resolve_datatype(p_assignable->datatype_specifier));
		type = specified_type;
	}