### 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)

static constexpr const char *kind = "constant";
	resolve_assignable(p_constant, kind);
#ifdef DEBUG_ENABLED
	if (p_is_local) {
		if (p_constant->usages == 0) {
			parser->push_warning(p_constant, GDScriptWarning::UNUSED_LOCAL_CONSTANT, p_constant->identifier->name);
		}
		is_shadowing(p_constant->identifier, kind);
	}
#endif
}
void GDScriptAnalyzer::resolve_parameter(GDScriptParser::ParameterNode *p_parameter) {
	static constexpr const char *kind = "parameter";
	resolve_assignable(p_parameter, kind);
}
void GDScriptAnalyzer::resolve_if(GDScriptParser::IfNode *p_if) {
	reduce_expression(p_if->condition);
	resolve_suite(p_if->true_block);
	p_if->set_datatype(p_if->true_block->get_datatype());
	if (p_if->false_block != nullptr) {
		resolve_suite(p_if->false_block);
		decide_suite_type(p_if, p_if->false_block);
	}
}
void GDScriptAnalyzer::resolve_for(GDScriptParser::ForNode *p_for) {