[mlir][Linalg] Add a hoistViewAllocOps helper function

This revision adds a helper function to hoist alloc/dealloc pairs and
alloca op out of immediately enclosing scf::ForOp if both conditions are true:
   1. all operands are defined outside the loop.
   2. all uses are ViewLikeOp or DeallocOp.

This is now considered Linalg-specific and will be generalized on a per-need basis.

Differential Revision: https://reviews.llvm.org/D81152