Make `Prover` generic over the `ConstraintCommitment` type #1377

Job	Run time
Check prover and winterfell packages	1m 1s
Check all features and all targets against the MSRV, except for winter-prover and winterfell	1m 39s
Light checks	38s
Test Rust stable on	1m 3s
Test Rust nightly on	1m 13s
Build for no-std (stable)	40s
Build for no-std (nightly)	38s
	6m 52s

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