### 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
if (E->get().start_line > warning.start_line) {
			break;
		}
		before = E;
	}
	if (before) {
		warnings.insert_after(before, warning);
	} else {
		warnings.push_front(warning);
	}
}
#endif
void GDScriptParser::make_completion_context(CompletionType p_type, Node *p_node, int p_argument, bool p_force) {
	if (!for_completion || (!p_force && completion_context.type != COMPLETION_NONE)) {
		return;
	}
	if (previous.cursor_place != GDScriptTokenizer::CURSOR_MIDDLE && previous.cursor_place != GDScriptTokenizer::CURSOR_END && current.cursor_place == GDScriptTokenizer::CURSOR_NONE) {
		return;
	}
	CompletionContext context;
	context.type = p_type;
	context.current_class = current_class;
	context.current_function = current_function;
	context.current_suite = current_suite;
	context.current_line = tokenizer.get_cursor_line();
	context.current_argument = p_argument;
	context.node = p_node;
	completion_context = context;
}
void GDScriptParser::make_completion_context(CompletionType p_type, Variant::Type p_builtin_type, bool p_force) {