[llvm] [mlir][bufferization] Empty tensor elimination for materialize_in_destination (PR #65468)

[via llvm-commits]

https://github.com/srcarroll commented:

most of my questions/comments are about `isEquivalentSubset`.  Obviously I'm having a hard time understanding the structure for this, so I'm hoping to get some clarity on it

https://github.com/llvm/llvm-project/pull/65468