title: Convert string enum type to union type of enum values
body: <p>How can I get a union type of a typescript string enum?</p>
  
  <pre><code>enum MyEnum {
    A = 'a', // Values are different from keys, so keyof will not help here.
    B = 'b',
  }
  </code></pre>
  
  <p>Given an enum type like the one above, how can I get the union type "a" | "b" ?</p>