[mlir][dxsa] Refactor Control Flow Instructions to use attribute-based operands

[tagolog]

Right now control flow instructions are in SSA form

module {
  %0 = dxsa.index.imm {imm = 0 : i32}
   %1 = dxsa.operand %0 {num_components = 4 : i32, one = 0 : i32, type = 0 : i32}
   dxsa.if <non_zero>, %1
}

Should be:

   dxsa.if_z r<0>
   ...
   dxsa.if_nz r<0>