Query String Parser

by Pig Fang @g-plane

You're required to implement a type-level parser to parse URL query string into a object literal type. Some detailed requirements: - Value of a key in query string can be ignored but still be parsed to `true`. For example, `'key'` is without value, so the parser result is `{ key: true }`. - Duplicated keys must be merged into one. If there are different values with the same key, values must be merged into a tuple type. - When a key has only one value, that value can't be wrapped into a tuple type. - If values with the same key appear more than once, it must be treated as once. For example, `key=value&key=value` must be treated as `key=value` only.