Proto/DAL/Sc_rollups: A better interface for Request_adal_page

When requesting a page in the Adjustable DAL context, it's better for kernels do not depend on the total number of shards because if that values evolve on L1 during a protocol upgrade, and the kernel didn't expect the modification (didn't upgrade or is not aware of the modification), its internal logic might be broken.

Exposing a ratio attestation_threshold_ppm (attestation threshold parts per million) allows being more generic.