[MLIR][Presburger] reintroduce int64_t versions of floorDiv, ceilDiv in mlir::presburger namespace

This is useful because MPInt.h defines identically-named functions that
operate on MPInts, which would otherwie become the only candidates of
overload resolution when calling e.g. ceilDiv from the mlir::presburger
namespace (iff MPInt.h is included). So to access the 64-bit overloads, an
explict call to mlir::ceilDiv would be required. This patch adds `using`
declarations allowing overload resolution to transparently call the right
function.

Reviewed By: Groverkss

Differential Revision: https://reviews.llvm.org/D129820