feat: `IntX` modulo lemmas (#7704)

This PR adds lemmas about the modulo operation defined on signed bounded
integers.

The results depend on the lemma
```lean
theorem BitVec.toInt_srem (a b : BitVec w) : (a.srem b).toInt = a.toInt.tmod b.toInt := sorry
```
which is missing at the time of posting the PR.
1 file changed