[InstCombine] fold mask op into casted shift (PR46013)

https://rise4fun.com/Alive/Qply8

  Pre: C2 == (-1 u>> zext(C1))
  %a = ashr %x, C1
  %s = sext %a to i16
  %r = and i16 %s, C2
    =>
  %s2 = sext %x to i16
  %r = lshr i16 %s2, zext(C1)

https://bugs.llvm.org/show_bug.cgi?id=46013