Adapt alerts to Patternfly
Currently our alerts have a h4 header, then a text. Alerts on Patternfly are meant to have a bold title, then the content, like one can see in https://www.patternfly.org/widgets/#alerts
Refs #13279 - checked_icon should use fa-check not png
toggle_check.png does not exist anymore and we can rely on the
font-awesome fa-check icon to display the check. Visit
provisioning_templates and see the Snippet column to see the icon.