[mlir][bufferization] Add pattern to BufferDeallocationSimplification pass...

[mlir][bufferization] Add pattern to BufferDeallocationSimplification pass that removes unnecessary retain values

Adds a pattern that removes memrefs from the `retained` list which are
guaranteed to not alias any memref in the `memrefs` list. The corresponding
result value can be replaced with `false` in that case according to the
operation description.

When applied after BufferDeallocation, this can considerably reduce the
overhead that needs to be added during the lowering of the dealloc operation to
check for aliasing (especially when there is only one element in the `memref`
list and all `retained` values can be removed).

Depends on D157398

Reviewed By: springerm

Differential Revision: https://reviews.llvm.org/D157407