These will be used by LeanSAT for bitblasting rotations by constant
distances.
We first reduce the case when the rotation amount is larger than the
width to the case where the rotation amount is less than the width
(`x.rotateLeft/Right r = x.rotateLeft/Right (r%w)`).
Then, we case analyze on the low bits versus the high bits of the
rotation, where we prove equality by extensionality.
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Co-authored-by: Alex Keizer <alex@keizer.dev>
Co-authored-by: Tobias Grosser <github@grosser.es>