### 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
*/
					int open_bracket_pos = begin_scan, close_bracket_pos = 0;
					while (open_bracket_pos < stripped_line.length() && (stripped_line[open_bracket_pos] == ' ' || stripped_line[open_bracket_pos] == '\t')) {
						open_bracket_pos++;
					}
					if (open_bracket_pos == stripped_line.length() || stripped_line[open_bracket_pos++] != '(') {
						continue; 
					}
					close_bracket_pos = open_bracket_pos;
					while (close_bracket_pos < stripped_line.length() && stripped_line[close_bracket_pos] != ')') {
						close_bracket_pos++;
					}
					if (close_bracket_pos == stripped_line.length()) {
						continue; 
					}
					int colon_pos = close_bracket_pos + 1;
					while (colon_pos < stripped_line.length() && (stripped_line[colon_pos] == ' ' || stripped_line[colon_pos] == '\t')) {
						colon_pos++;
					}
					if (colon_pos == stripped_line.length() || stripped_line[colon_pos++] != ':') {
						continue; 
					}
					title = stripped_line.substr(open_bracket_pos, close_bracket_pos - open_bracket_pos).strip_edges();
					link = stripped_line.substr(colon_pos).strip_edges();
				}
				mode = TUTORIALS;
			} else if (mode == TUTORIALS) { 
				mode = DONE;
			}
		}