feat(gpodder): add admin paginated users method

gpodder_sqlite/src/repository/auth.rs

@@ -142,4 +142,17 @@ impl gpodder::GpodderAuthStore for SqliteRepository {
         })()
         .map_err(AuthErr::from)
     }
+
+    fn paginated_users(&self, page: gpodder::Page) -> Result<Vec<gpodder::User>, AuthErr> {
+        Ok(users::table
+            .select(User::as_select())
+            .order(users::username.asc())
+            .offset((page.page * page.per_page) as i64)
+            .limit(page.per_page as i64)
+            .get_results(&mut self.pool.get().map_err(DbError::from)?)
+            .map_err(DbError::from)?
+            .into_iter()
+            .map(gpodder::User::from)
+            .collect())
+    }
 }