Basic crud page generators for models

[eric-burel]

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Describe the solution you'd like
Being able to run CRUD operations on any collection + demo all the available hooks and patterns to do CRUD operations in Vulcan (hooks and smart form).

This is both for learning and for direct usage.

• Setup the pages
• Add _middleware in front of /admin folder to do a server-side redirect
• Add currentUser management in SmartForm. We need to code a useCurrentUser hook and use it in the form

Describe alternatives you've considered

See an early demo of this kind of page: https://github.com/VulcanJS/vulcan-next/blob/940c6c680a41f29cb9f7af5ae2b93f8d39bd762b/src/pages/meteor-demo.tsx

See previous implementation in Vulcan Meteor: VulcanJS/Vulcan#2176

• Create the same page for a basic model in Vulcan Next
• Then, create the same page for a list of models, using static generation
  => you get an admin area

[eric-burel]

First version has been implemented by @Timi-Duban and visilble in the /admin page

Next step:

• figuring user creation (difficult because of the password)
• fix currentUser handling in SmartForm so private fields are present

Then we can call it a v1