feat: BitVec normalization rule for udiv by twoPow #6029
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This PR adds a normalization rule to `bv_normalize` (which is used by `bv_decide`) that converts `x / 2^k` into `x >>> k` under suitable conditions. This allows us to simplify the expensive division circuits that are used for bitblasting into much cheaper shifting circuits. Concretely, it allows for the following canonicalization:
```lean
example {x : BitVec 16} : x / (BitVec.twoPow 16 2) = x >>> 2 := by bv_normalize
example {x : BitVec 16} : x / (BitVec.ofNat 16 8) = x >>> 3 := by bv_normalize
```
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This PR adds a normalization rule to
bv_normalize(which is used bybv_decide) that convertsx / 2^kintox >>> kunder suitable conditions. This allows us to simplify the expensive division circuits that are used for bitblasting into much cheaper shifting circuits. Concretely, it allows for the following canonicalization: