This PR both adds initial `@[grind]` annotations for `BitVec`, and uses
`grind` to remove many proofs from `BitVec/Lemmas`.
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Co-authored-by: Sebastian Ullrich <sebasti@nullri.ch>
This PR avoids importing all of `BitVec.Lemmas` and `BitVec.BitBlast`
into `UInt.Lemmas`. (They are still imported into `SInt.Lemmas`; this
seems much harder to avoid.)