[mlir][arith] Disallow casting tensor dimensions (#93349)

Tighten the verifier for arith cast ops to disallow changing tensor
dimensions, e.g., static to dynamic. After this change:
* `arith.cast_op %x : tensor<4xi32> to tensor<4xf32>` remains valid
* `arith.cast_op %x : tensor<4xi32> to tensor<?xf32>` becomes invalid
* `arith.cast_op %x : tensor<?xi32> to tensor<4xf32>` becomes invalid

This is mostly to simplify the op semantics. See the discussion thread
for more context:
https://discourse.llvm.org/t/rfc-remove-arith-math-ops-on-tensors/74357/63.