Improve notifications (#16632)

* add notification cooldown

* cooldown docs

* show alert box when notifications are used in an insecure context

* add ability to suspend notifications from dashboard context menu

docs/docs/configuration/notifications.md

@@ -11,14 +11,37 @@ Frigate offers native notifications using the [WebPush Protocol](https://web.dev
 
 In order to use notifications the following requirements must be met:
 
-- Frigate must be accessed via a secure https connection
+- Frigate must be accessed via a secure `https` connection ([see the authorization docs](/configuration/authentication)).
 - A supported browser must be used. Currently Chrome, Firefox, and Safari are known to be supported.
-- In order for notifications to be usable externally, Frigate must be accessible externally
+- In order for notifications to be usable externally, Frigate must be accessible externally.
 
 ### Configuration
 
 To configure notifications, go to the Frigate WebUI -> Settings -> Notifications and enable, then fill out the fields and save.
 
+Optionally, you can change the default cooldown period for notifications through the `cooldown` parameter in your config file. This parameter can also be overridden at the camera level.
+
+Notifications will be prevented if either:
+
+- The global cooldown period hasn't elapsed since any camera's last notification
+- The camera-specific cooldown period hasn't elapsed for the specific camera
+
+```yaml
+notifications:
+  enabled: True
+  email: "johndoe@gmail.com"
+  cooldown: 10 # wait 10 seconds before sending another notification from any camera
+```
+
+```yaml
+cameras:
+  doorbell:
+    ...
+    notifications:
+      enabled: True
+      cooldown: 30 # wait 30 seconds before sending another notification from the doorbell camera
+```
+
 ### Registration
 
 Once notifications are enabled, press the `Register for Notifications` button on all devices that you would like to receive notifications on. This will register the background worker. After this Frigate must be restarted and then notifications will begin to be sent.
@@ -39,4 +62,4 @@ Different platforms handle notifications differently, some settings changes may
 
 ### Android
 
-Most Android phones have battery optimization settings. To get reliable Notification delivery the browser (Chrome, Firefox) should have battery optimizations disabled. If Frigate is running as a PWA then the Frigate app should have battery optimizations disabled as well.
+Most Android phones have battery optimization settings. To get reliable Notification delivery the browser (Chrome, Firefox) should have battery optimizations disabled. If Frigate is running as a PWA then the Frigate app should have battery optimizations disabled as well.

docs/docs/configuration/reference.md

@@ -420,6 +420,8 @@ notifications:
   # Optional: Email for push service to reach out to
   # NOTE: This is required to use notifications
   email: "admin@example.com"
+  # Optional: Cooldown time for notifications in seconds (default: shown below)
+  cooldown: 0
 
 # Optional: Record configuration
 # NOTE: Can be overridden at the camera level