A failing debug assertion or overflow without correctly wrapping or
saturating is a bug, but the `debug` profile that has these enabled does
not run enough test cases to hit edge cases that may trigger these. Add
a new `release-checked` profile that enables debug assertions and
overflow checks. This seems to only extend per-function test time by a
few seconds (or around a minute on longer extensive tests), so enable
this as the default on CI.
In order to ensure `no_panic` still gets checked, add a build-only step
to CI.
5c94cce6b2