stark-backend

This crate provides the traits of the SWIRL protocol, the verifier, and a reference column-major CPU prover backend (CpuColMajorBackend in src/prover/cpu_backend.rs). The optimized row-major CPU prover backend lives in the separate openvm-cpu-backend crate. All traits and implementations in this crate must be generic to the field. Concrete specializations should be provided in the openvm-stark-sdk crate. To avoid a circular dependency, openvm-stark-sdk is a dev-dependency that should only used in integration tests. As such, most tests of the protocol are integration tests.