AC: Spring Security Helper

[haijian-vaadin]

As a developer
I want the Vaadin framework to take care of the Vaadin related Security config for me.
So that I only need to do application-specific Spring Security configs.

Acceptance criteria

• (Subjective) When protecting the application behind a login view, There should be fewer lines of boilerplate code should be less than compared with V19.
• If user has an existing V19 application, with the new security helper in place, then I can change the Security config class by extending from the helper class, then the Vaadin specific configuration is no longer needed.
• The user is instructed to use the new helper class, and where to put the application-specific configurations.

General criteria

• APIs reviewed
  The original API was designed through the GitHub issue
  Then made changes based on the feedbacks in the DX testing

• UX/DX tests in Alpha
  https://docs.google.com/document/d/19h3iynuEgryz3TnTACQYw6OxQycUkRjodbwUnwKiPyE/edit

• Documentation:
  https://vaadin.com/docs/latest/fusion/security/spring-login

• How to test?
  https://docs.google.com/document/d/1tGBUT6a9Jzyi2gTMO90F6kUxl0CoZfZmq0VfcORC77o/edit#

Description

Less boilerplate code for configuring Spring Security, more time to focus on the business logic, more productive.