Fixes: #18184 - Gracefully handle unavailable internet connection on RSS feed dashboard widget if ISOLATED_DEPLOYMENT is set (#18186)

* Suppress adding the RSS feed widget to the dashboard if ISOLATED_DEPLOYMENT is set

* Add config option on RSSFeedWidget to specify requires_internet and to display a more appropriate error if ISOLATED_DEPLOYMENT is set

* Remove skipping behavior from utils.py

* Add required=False

netbox/extras/dashboard/widgets.py

@@ -275,6 +275,7 @@ class RSSFeedWidget(DashboardWidget):
     default_config = {
         'max_entries': 10,
         'cache_timeout': 3600,  # seconds
+        'requires_internet': True,
     }
     description = _('Embed an RSS feed from an external website.')
     template_name = 'extras/dashboard/widgets/rssfeed.html'
@@ -285,6 +286,10 @@ class RSSFeedWidget(DashboardWidget):
         feed_url = forms.URLField(
             label=_('Feed URL')
         )
+        requires_internet = forms.BooleanField(
+            label=_('Requires external connection'),
+            required=False,
+        )
         max_entries = forms.IntegerField(
             min_value=1,
             max_value=1000,
@@ -309,6 +314,11 @@ class RSSFeedWidget(DashboardWidget):
         return f'dashboard_rss_{url_checksum}'
 
     def get_feed(self):
+        if self.config['requires_internet'] and settings.ISOLATED_DEPLOYMENT:
+            return {
+                'isolated_deployment': True,
+            }
+
         # Fetch RSS content from cache if available
         if feed_content := cache.get(self.cache_key):
             return {