T4934: ospf: Fix inter-area route summarization

Setting something like `protocols ospf area 10 range 10.10.0.0/16` without sub options doesn't work. This is because no range commands are generated when there is no leaf nodes set under the `range` tag node.

```
edit protocols ospf
set area 16 network 10.10.0.0/16
set area 16 range 10.10.0.0/16
commit
```

```
$ vtysh -c 'show run'
!
router ospf
 auto-cost reference-bandwidth 100
 timers throttle spf 200 1000 10000
 network 10.10.0.0/16 area 16
exit
```

The generated FRR commands above is missing something like:

```
 area 16 range 10.10.0.0/16
```

data/templates/frr/ospfd.frr.j2

@@ -84,11 +84,13 @@ router ospf {{ 'vrf ' ~ vrf if vrf is vyos_defined }}
 {%         endfor %}
 {%         if area_config.range is vyos_defined %}
 {%             for range, range_config in area_config.range.items() %}
-{%                 if range_config.cost is vyos_defined %}
- area {{ area_id }} range {{ range }} cost {{ range_config.cost }}
-{%                 endif %}
 {%                 if range_config.not_advertise is vyos_defined %}
  area {{ area_id }} range {{ range }} not-advertise
+{%                 else %}
+ area {{ area_id }} range {{ range }}
+{%                 endif %}
+{%                 if range_config.cost is vyos_defined %}
+ area {{ area_id }} range {{ range }} cost {{ range_config.cost }}
 {%                 endif %}
 {%                 if range_config.substitute is vyos_defined %}
  area {{ area_id }} range {{ range }} substitute {{ range_config.substitute }}

smoketest/scripts/cli/test_protocols_ospf.py

@@ -75,6 +75,9 @@ def test_ospf_02_simple(self):
         self.cli_set(base_path + ['log-adjacency-changes', 'detail'])
         self.cli_set(base_path + ['default-metric', metric])
         self.cli_set(base_path + ['passive-interface', 'default'])
+        self.cli_set(base_path + ['area', '10', 'network', '10.0.0.0/16'])
+        self.cli_set(base_path + ['area', '10', 'range', '10.0.1.0/24'])
+        self.cli_set(base_path + ['area', '10', 'range', '10.0.2.0/24', 'not-advertise'])
 
         # commit changes
         self.cli_commit()
@@ -90,6 +93,11 @@ def test_ospf_02_simple(self):
         self.assertIn(f' capability opaque', frrconfig)
         self.assertIn(f' default-metric {metric}', frrconfig)
         self.assertIn(f' passive-interface default', frrconfig)
+        self.assertIn(f' area 10 stub', frrconfig)
+        self.assertIn(f' area 10 network 10.0.0.0/16', frrconfig)
+        self.assertIn(f' area 10 range 10.0.1.0/24', frrconfig)
+        self.assertNotIn(f' area 10 range 10.0.1.0/24 not-advertise', frrconfig)
+        self.assertIn(f' area 10 range 10.0.2.0/24 not-advertise', frrconfig)
 
 
     def test_ospf_03_access_list(self):