message: shared: make separator optional in joinGrammaticallyListOfItems
diff: import * as _ from 'lodash';
  -export const joinGrammaticallyListOfItems = (items: string[]) => {
  +export const joinGrammaticallyListOfItems = (items: string[], separator = 'and') => {
  const result = items.join(', ');
  const lastCommaIdx = result.lastIndexOf(',');
  return items.length > 1 && lastCommaIdx >= 0
  - ? `${result.substr(0, lastCommaIdx)} and${result.substr(lastCommaIdx + 1)}`
  + ? `${result.substr(0, lastCommaIdx)} ${separator}${result.substr(lastCommaIdx + 1)}`
  : result;
  };
  