support custom propertyNames

[theoephraim]

I'd like to be able to explicitly specify (via a new comment) some info about the keys of an object. Something like:

type ObjectWithKeysOfSpecificFormat = {
  /** @TJS-propertyNames.pattern '^someprefix_\d+$' */
  [keyWithFormat: string]: {
    foo: string,
    ...
  }
}