Adds an end-to-end test for `tensor.unpack` with dynamic inner tile sizes.
While relatively simple (e.g., no vectorization), this example required a few
fixes in handling `tensor.unpack` (and similar fixes for `tensor.pack` before
that):
* #119379, #121393, #121400.
The end goal for this test is to incrementally increase its complexity
and to work towards scalable tile sizes.
Note, this PR complements #115698 in which similar test for
`tensor.pack` was added.
dfa5ee2af2