feat: add user specific notification settings

The settings can be customized for each origin and each processor
individually. The default Web indicates notifications shown in the
Backstage UI. By default, if there are no settings saved in the
database, all notifications are enabled for all processors.

The origins will populate by time for each user as they receive the
first notification from that origin. Processors are shown as their own
columns.

Later, if it makes sense, allow users to also disable/enable
notifications based on notification topic.

Signed-off-by: Heikki Hellgren <heikki.hellgren@op.fi>

plugins/scaffolder-backend/sample-templates/all-templates.yaml

@@ -6,6 +6,7 @@ metadata:
 spec:
   targets:
     - ./remote-templates.yaml
+    - ./notifications-demo/template.yaml
 # For local development of a template, you can reference your local templates here.
 # Examples:
 #

plugins/scaffolder-backend/sample-templates/notifications-demo/template.yaml

@@ -0,0 +1,69 @@
+apiVersion: scaffolder.backstage.io/v1beta3
+kind: Template
+metadata:
+  name: notifications-demo
+  title: Test Notifications template
+  description: scaffolder v1beta3 template demo sending notification
+spec:
+  owner: backstage/techdocs-core
+  type: service
+  parameters:
+    - title: Notification
+      required:
+        - recipients
+        - title
+      properties:
+        recipients:
+          title: Recipients
+          type: string
+          description: Notification recipients
+          default: entity
+          enum:
+            - entity
+            - broadcast
+        entityRefs:
+          title: Entities
+          type: array
+          description: Entities to send the notification. Required if recipients is entity
+          ui:field: MultiEntityPicker
+          ui:options:
+            defaultNamespace: default
+        title:
+          title: Title
+          type: string
+          description: Notification title
+        description:
+          title: Description
+          type: string
+          description: Notification longer description
+        link:
+          title: Link
+          type: string
+          description: Notification link
+        severity:
+          title: Severity
+          type: string
+          description: Notification severity
+          default: normal
+          enum:
+            - low
+            - normal
+            - high
+            - critical
+        scope:
+          title: Scope
+          type: string
+          description: Notification scope
+
+  steps:
+    - id: send-notification
+      name: Send notification
+      action: notification:send
+      input:
+        recipients: ${{ parameters.recipients }}
+        entityRefs: ${{ parameters.entityRefs }}
+        title: ${{ parameters.title }}
+        description: ${{ parameters.description }}
+        link: ${{ parameters.link }}
+        severity: ${{ parameters.severity }}
+        scope: ${{ parameters.scope }}