[mlir][tensor] Fold `tensor.cast` into `tensor.collapse_shape` op

[mlir][tensor] Fold `tensor.cast` into `tensor.collapse_shape` op

This commit folds a `tensor.cast` op into a `tensor.collapse_shape` op
when following two conditions meet:
1. the `tensor.collapse_shape` op consumes result of the `tensor.cast` op.
2. `tensor.cast` op casts to a more dynamic version of the source tensor.
This is added as a canonicalization pattern in `tensor.collapse_shape` op.

Signed-Off-By: Gaurav Shukla <gaurav@nod-labs.com>
Reviewed By: mravishankar

Differential Revision: https://reviews.llvm.org/D130650