feat(data/rat/defs): inv_coe_{int,nat}_{num,denom} (#15863)
Rename existing lemmas to
`inv_coe_{int,nat}_{num,denom}_of_pos`
since they took positivity assumptions
Also provide `rat.inv_neg`.
Co-authored-by: Yakov Pechersky <pechersky@users.noreply.github.com>
