Add support for slickpg column extensions with ValueClassLike and InstanceConverter

Using a tagged type 
```
@tagged trait Domain {

  trait UserEmailTag
  type UserEmail = String @@ UserEmailTag
}

object UserDomain extends Domain {}
```
 with `PgStringSupport` produces the following error:
```
value ilike is not a member of slick.lifted.Rep[mypackage.UserDomain.UserEmail]
```