[Refactor] Remove unsigned attributes #213
Description
As Allo now has a strong type system with comprehensive typing rules, we may try to remove the legacy unsigned attributes in the generated MLIR code. These attributes actually increase the maintenance cost from the frontend to backend, and are not fully compatible with the native MLIR ecosystem.
The issues mentioned in cornell-zhang/hcl-dialect#7 seem to be resolved after we had the type system.