emoji_eventsParse a query string

Write parseQuery(qs) that turns a URL query string into an object, without URLSearchParams.

• A leading ? is optional: "?page=2&q=flask" gives { page: "2", q: "flask" }.
• Values are URL-decoded, and + means a space.
• A key that appears more than once gives an array of values, in order.
• A key without = gets an empty string.

Acceptance criteria

• An empty string gives {}.
• The tests at the bottom print All tests passed.