Wal-Mart, the nation’s largest retailer, will announce Tuesday a plan to hire every veteran who wants a job, provided that the veterans have left the military in the previous year and did not receive a dishonorable discharge. Company officials said they believe the program, which will officially begin on Memorial Day — May 27 this year — will lead to the hiring of more than 100,000 people in the next five years, the length of the commitment.  “Let’s be clear: Hiring a veteran can be one of the best decisions any of us can make,” Mr. Simon will say in his keynote speech to the National Retail Federation, according to prepared text. “These are leaders with discipline, training and a passion for service.”