Feat: Ability to switch editions to review other editions

[iJungleboy]

I'm submitting a

[x] feature request

...about

[x] edit experience / UI
[x] admin experience UI
[x] Razor templating
[x] Polymorphism

Current Behavior / Expected Behavior

ATM certain users such as super-users see staging, normal users see live.

In some cases the super-user would like to see live to compare, and admins may want to see staging to preview some changes.

• Refactor polymorphism to use latest setup Refactor: Polymorphism should use classic SwitchableService architecture #3385
• create UI to save a session cookie like app-ID-edition=edition in the layout area
• implement backend to respect this cookie, but only if allowed
• extend configuration to allow the admin to set other users who can see this
• ensure backend allows these users too
• find way to tell UI about available editions + if user may switch

Your environment

• 2sxc version(s): 17.07