Introduce `PostPublicViewMessage` and `PostPublicViewMessageHandler` to handle external user views on public links by applying workflow transitions. Integrate with `WorkflowViewSendPublicController` and add relevant tests.
Introduced the ability to render public views for workflows, including new templates, handlers, and metadata support. Updated entity interfaces and translations to enhance the public sharing of workflow documents.
- create an event subscriber to catch the workflow which arrive to a "sentExternal" step;
- add a messenger's message to handle the generation of the email;
- add a simple message, and a simple controller for viewing the document
- add dedicated tests
