### 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
return parse_precedence(PREC_ASSIGNMENT, p_can_assign, p_stop_on_assign);
}
GDScriptParser::IdentifierNode *GDScriptParser::parse_identifier() {
	IdentifierNode *identifier = static_cast<IdentifierNode *>(parse_identifier(nullptr, false));
#ifdef DEBUG_ENABLED
	
	if (identifier && TS->has_feature(TextServer::FEATURE_UNICODE_SECURITY) && TS->spoof_check(identifier->name.operator String())) {
		push_warning(identifier, GDScriptWarning::CONFUSABLE_IDENTIFIER, identifier->name.operator String());
	}
#endif
	return identifier;
}
GDScriptParser::ExpressionNode *GDScriptParser::parse_identifier(ExpressionNode *p_previous_operand, bool p_can_assign) {
	if (!previous.is_identifier()) {
		ERR_FAIL_V_MSG(nullptr, "Parser bug: parsing identifier node without identifier token.");
	}
	IdentifierNode *identifier = alloc_node<IdentifierNode>();
	complete_extents(identifier);
	identifier->name = previous.get_identifier();
	if (current_suite != nullptr && current_suite->has_local(identifier->name)) {
		const SuiteNode::Local &declaration = current_suite->get_local(identifier->name);
		identifier->source_function = declaration.source_function;
		switch (declaration.type) {
			case SuiteNode::Local::CONSTANT:
				identifier->source = IdentifierNode::LOCAL_CONSTANT;