[wp] Generalize overflow tactic

src/plugins/wp/Lang.ml

src/plugins/wp/Lang.mli

src/plugins/wp/TacOverflow.ml

...inaryMultiplication_loop_invariant_inv1_ok_preserved.json

...e_qualif/overflow.0.session/script/lemma_j_incr_char.json

..._qualif/overflow.0.session/script/lemma_j_incr_short.json

...plugins/wp/tests/wp_tip/oracle_qualif/overflow.res.oracle

src/plugins/wp/tests/wp_tip/overflow.i