chore: move BitVec.udiv/umod/sdiv/smod after add/sub/mul/lt (#5623)

Divison proofs are more likely to depend on add/sub/mul proofs than the
other way around. This cleans up
https://github.com/leanprover/lean4/pull/5609, which added division
proofs that rely on negation to already be defined.
1 file changed