[FR]: new Notification action

[vran-dev]

Description
Introduce a new action called Notification that allows users to send custom in-app or system notifications during workflow execution.

Details

• Users can configure the following fields:
  • Title (required): The notification title. Supports form variables and dynamic expressions (e.g., {{@name}}).
  • Message (optional): The notification body/content. Also supports form variables and dynamic expressions.
• If the message field is left empty, only the title will be displayed (useful for simple alerts).

Use Cases

• Notify users when a form is successfully submitted