Use a less generic name for the RPO-STARK-based signature scheme

We should substitute the generic name for the STARK-based signature scheme with something less generic.

Look for references to the RPO-STARK-based signature scheme in the codebase, likely in cryptographic modules or signature-related files. Determine the current generic name used and propose a more specific alternative. Check if there are tests or documentation that also need updating to reflect the name change.

Written by the indexing model from the issue text.