NEW YORK — Starbucks Workers United held a rally outside the Empire State Building on Thursday as its open-ended strike entered its third week and no signs of an impending resolution. Adding to the crunch of holiday shoppers and tourists, several hundred picketers gathered outside of the famous landmark, which is also the site of a swanky three-floor Starbucks Reserve location and the company's regional headquarters. Members of other unions, like the AFL-CIO and Service Employees International