We need a way for users to easily enable / disable the new UI.

After the SIG meeting on 5th Feb:

• there’s no planned work to make Jenkins customized per user
• Admin users will be able to toggle between UIs using a check in the manage Jenkins page.

Besides, in case the plans change in the future and the capability of customizing Jenkins per users become something real, this approach will allow us to migrate from the manage Jenkins page (http://localhost:7080/configure), where the admin might set a global style, to the configuration page where each user can manage themselves (http://localhost:7080/user/noadminuser/configure)

Acceptance criteria

• Create a simple system that would toggle between the new and the former UI from a user interaction