Provide a visual notification in wp-admin for pending listings that require approval.

### Is your feature request related to a problem? Please describe
Currently, when there is a pending Job Listing that requires admin approval, admins are only notified via email.

### Describe the solution you'd like
Have a visual notification like a banner to remind admins of pending listings that require approval or number on the jobs listing admin menu.

### Additional context
3541924-zen

Start by locating the wp-admin jobs listing admin menu and the pending listing approval flow. Determine whether the intended notification is a banner or a count on the menu; done means admins can visibly identify pending listings requiring approval without relying on email.

Written by the indexing model from the issue text.