🐛 Fixed default recipients setting not showing label filters

problem: when the Default Recipient setting is set to "Specific people" and is filtered by a label, we were not able to render the label correctly
cause: during the rendering, we look for labels by id, but they're stored by slug in the database setting editor_default_email_recipients_filter
solution: allow to look by the relevant key, by introducing a programmatic key to search for

TryGhost / Ghost