`ppr-to-mbqc` pass does not support `qec.ppr.arbitrary` operations

[sengthai]

The ppr-to-mbqc pass currently only supports qec.ppr (fixed-angle) and qec.ppm operations. When encountering a qec.ppr.arbitrary operation, it emits an error: Unsupported qec.ppr.arbitrary operation.

The pass should lower qec.ppr.arbitrary operations to MBQC-style gate sequences, similar to how it handles fixed-angle PPR operations.