### 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 (int i = 0; i < p_suite->statements.size(); i++) {
		print_statement(p_suite->statements[i]);
	}
}
void GDScriptParser::TreePrinter::print_ternary_op(TernaryOpNode *p_ternary_op) {
	
	push_text("(");
	print_expression(p_ternary_op->true_expr);
	push_text(") IF (");
	print_expression(p_ternary_op->condition);
	push_text(") ELSE (");
	print_expression(p_ternary_op->false_expr);
	push_text(")");
}
void GDScriptParser::TreePrinter::print_type(TypeNode *p_type) {
	if (p_type->type_chain.is_empty()) {
		push_text("Void");
	} else {
		for (int i = 0; i < p_type->type_chain.size(); i++) {
			if (i > 0) {
				push_text(".");
			}
			print_identifier(p_type->type_chain[i]);
		}
	}
}
void GDScriptParser::TreePrinter::print_type_test(TypeTestNode *p_test) {