Baked Table::buildRules() rules are too brief.

[beporter]

You get something like this:

$rules->add($rules->isUnique(['email']));

When really we want something like this:

$rules->add(
    $rules->isUnique(['email']),
    'email-is-unique',
    [
        'errorField' => 'email',
        'message' => 'That email address already exists.',
    ]
);

Without those additional properties, the rule will cause a save() to fail, but will not report the error anywhere (not even in DebugKit). This is not an acceptable "default" level of quality. We should have the choice to reduce the "verbosity" of the messages, not be forced to add it by rote. That's the whole point of having bake templates, after all.