Add a warning on non-test analysis w/o foundry_success checking

[palinatolmach]

Related: #312

In Kontrol, we only check foundry_success predicate (and, therefore, report the test as failing) if the name of the test starts with test, check, or prove (#249). Once #312 is fixed, we'll be able to also check hevm_success predicate.

However, right now, if the test doesn't start from one of these three prefixes, it is being symbolically explored, but does not get reported as failing even if the test reverts. As reported by @dwightguth, it is confusing and looks like a bug, so we should probably emit a warning that informs the user that the test is not being checked for failures.

[ehildenb]

This is intended behavior though for methods without test_ prefix, so that the user can create a summary to be used in running other tests/functions (via the --include-summary ... option). So a warning seems too strong here, maybe some documentation, or an INFO log.