### Godot version

4.0 stable

### System information

Fedora, RX 590

### Issue description

I made a dictionary, and instead of using `:` to separate between key and value, i accidentally used `=`.
The error message was not clear at all `Parse Error: Expected identifier or string as LUA-style dictionary key.` 

I don't think assuming that people know how dictionaries are made in LUA is reasonable. And if this is not about LUA the programming language, i don't even know what this is about :D

I think this error should be replaced with something of the sort "Please use `:` as separator instead of `=` in your dictionary"

### Steps to reproduce

Paste this code in a script:

```

var dict = {
	1 = "lala"
}
```

Observe the error message
![image](https://user-images.githubusercontent.com/7917475/224549538-38ea25aa-ba75-431e-868b-0733a53b90ad.png)


### Minimal reproduction project

see above
for (const AnnotationNode *E : p_variable->annotations) {
		print_annotation(E);
	}
	push_text("Variable ");
	print_identifier(p_variable->identifier);
	push_text(" : ");
	if (p_variable->datatype_specifier != nullptr) {
		print_type(p_variable->datatype_specifier);
	} else if (p_variable->infer_datatype) {
		push_text("<inferred type>");
	} else {
		push_text("Variant");
	}
	increase_indent();
	push_line();
	push_text("= ");
	if (p_variable->initializer == nullptr) {
		push_text("<default value>");
	} else {
		print_expression(p_variable->initializer);
	}
	push_line();
	if (p_variable->property != VariableNode::PROP_NONE) {
		if (p_variable->getter != nullptr) {
			push_text("Get");