By Ted Hesson WASHINGTON (Reuters) -Former U.S. President Donald Trump, the leading candidate for the Republican presidential nomination in 2024, has promised to crack down on illegal immigration and restrict legal immigration if elected to a second four-year term in office. Here are some of the policies under consideration: BORDER ENFORCEMENT Trump has said he would restore his 2019 “remain in Mexico” program, which forced non-Mexican asylum-seekers attempting to enter the United States at the Mexican border to wait in Mexico for the resolution of their cases. The program was terminated by Pr…