Add string initializers to an enum

Change Typescript enum so that it has string initializers.

Input

const enum TestkitType {
  vanilla,
  unidriver,
  protractor,
  puppeteer,
  unknown,
}

Output

const enum TestkitType {
  vanilla = 'VANILLA',
  unidriver = 'UNIDRIVER',
  protractor = 'PROTRACTOR',
  puppeteer = 'PUPPETEER',
  unknown = 'UNKNOWN',
}