Add a rewrite rule for equality of Nats and BVs.
Add a rewrite rule for equality of Nats and BVs.

equalNat i (bvToNat n x) == bvEq n (bvNat n i) x
GaloisInc/saw-script,GaloisInc/saw-script,GaloisInc/saw-script,GaloisInc/saw-script,GaloisInc/saw-script