views: Indicate configuring/enabling notifications if checkbox disabled.

This commit adds an extra Text widget in the stream settings indicating the
user to configure or enable notifications if the checkbox is disabled.

Currently, there are two ways to enable notifications in ZT:
- Pass the --notify flag when starting ZT.
- Add notify=enabled in the zuliprc file.
See https://github.com/zulip/zulip-terminal#notifications for details on
configuring notifications for your platform.

Author: zee-bit

zulipterminal/ui_tools/views.py

@@ -1299,10 +1299,18 @@ def __init__(self, controller: Any, stream_id: int) -> None:
             footlinks_width,
             len(visual_notification.label) + 4,
         )
+        visual_notification = [visual_notification]
+        # If notifications is not configured or enabled by the user, then
+        # disable the checkbox and mention it explicitly with a suffix text
         if not self.controller.notify_enabled:
-            visual_notification = urwid.WidgetDisable(
-                urwid.AttrMap(visual_notification, "widget_disabled")
-            )
+            visual_notification = [
+                urwid.WidgetDisable(
+                    urwid.AttrMap(*visual_notification, "widget_disabled")
+                ),
+                urwid.Text(
+                    ("popup_important", "    [notifications not configured or enabled]")
+                ),
+            ]
         self.widgets = self.make_table_with_categories(
             stream_info_content, column_widths
         )
@@ -1317,7 +1325,7 @@ def __init__(self, controller: Any, stream_id: int) -> None:
 
         self.widgets.append(muted_setting)
         self.widgets.append(pinned_setting)
-        self.widgets.append(visual_notification)
+        self.widgets.extend(visual_notification)
         super().__init__(controller, self.widgets, "STREAM_DESC", popup_width, title)
 
     def toggle_mute_status(self, button: Any, new_state: bool) -> None: