SEOUL (Reuters) -South Korea's former first lady Kim Keon Hee will spend her first day in jail on Wednesday in a cell much like the one her husband and ex-President Yoon Suk Yeol occupies as prosecutors pursue the once high-flying couple in a widening criminal probe. Kim was imprisoned after a court approved a warrant for her arrest late on Tuesday on the grounds that she might destroy evidence amid an ongoing investigation into allegations of bribery, stock fraud and influence peddling.