[mlir][LLVMIR] Add lifetime start and end marker instrinsics

This patch adds the `llvm.intr.lifetime.start` and `llvm.intr.lifetime.end`
intrinsics which are used to indicate to LLVM the lifetimes of allocated
memory.

These ops have the requirement that the first argument (the size) be an
"immediate argument". I added an OpTrait to check this, but it is
possible that an approach like GEPArg would work too.

Reviewed By: rriddle, dcaballe

Differential Revision: https://reviews.llvm.org/D133867