Return single item or item[] based on thing

[kearfy]

Motivation

Currently, the helper functions simply return either a single item or an array of items.
This PR is not optimal, but the best way to handle this as far as I can see.

How does this PR work?

Essentially, when you define a variable:

const userId = 'user:tobie';

Then typescript is smart enough to be able to compare it against a type like:

type Thing = `${string}:${string}`;

// Hint: The type is true :)
type userIdIsThing = 
    (typeof userId) extends Thing ? true : false; 

---

Put it to practice

import { Surreal, Thing } from 'surrealdb.js';

const surreal: Surreal;
type User = {
    id: Thing;
    name: string;
};

// Returns type "User[]" (as a promise)
const result = await surreal.select<User>('user');

// Returns type "User" (as a promise)
const result = await surreal.select<User>('user:tobie');

// Downside is that if the type is not clear, you'll have to force the type yourself if you know that it's of type "string:string"
// When you store a variable as a plain text in your code, typescript is smart enough to resolve the contents of the string
// Assume params is of type "Record<string, string>"
const { user } = params;

// Returns type "User" (as a promise)
const result = await surreal.select<User>(user as Thing);
// OR...
const result = await surreal.select<User, Thing>(user);