### 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
switch (p_variable->property) {
		case VariableNode::PROP_INLINE: {
			FunctionNode *function = alloc_node<FunctionNode>();
			consume(GDScriptTokenizer::Token::COLON, R"(Expected ":" after "get".)");
			IdentifierNode *identifier = alloc_node<IdentifierNode>();
			complete_extents(identifier);
			identifier->name = "@" + p_variable->identifier->name + "_getter";
			function->identifier = identifier;
			function->is_static = p_variable->is_static;
			FunctionNode *previous_function = current_function;
			current_function = function;
			SuiteNode *body = alloc_node<SuiteNode>();
			function->body = parse_suite("getter declaration", body);
			p_variable->getter = function;
			current_function = previous_function;
			complete_extents(function);
			break;
		}
		case VariableNode::PROP_SETGET:
			consume(GDScriptTokenizer::Token::EQUAL, R"(Expected "=" after "get")");
			make_completion_context(COMPLETION_PROPERTY_METHOD, p_variable);
			if (consume(GDScriptTokenizer::Token::IDENTIFIER, R"(Expected getter function name after "=".)")) {
				p_variable->getter_pointer = parse_identifier();
			}
			break;
		case VariableNode::PROP_NONE:
			break; 
	}
}
GDScriptParser::ConstantNode *GDScriptParser::parse_constant(bool p_is_static) {