Las Vegas Sands Corp. has reached a definitive agreement to sell its Sands Bethlehem casino to an American Indian tribe from Alabama. It’s a move that would unload arguably Pennsylvania’s most successful casino — and one of the Lehigh Valley’s largest employment hubs — to a little-known, yet cash-flush, group looking to grow. Wind Creek Hospitality, a privately held affiliate of the Poarch Band of Creek Indians of Alabama, is acquiring the property for a total enterprise value — market capitalization plus debt — of $1.3 billion, representing one of the largest sales in the Lehigh Valley’s history. The 159,000-square-foot…