Improovment on "ALM" for App thanks to Multiple Sources Models / Preview Function

It's very useful to have multiple sources models for one App in order to have our DEV and PROD model together. 

However, we nee to improove some functionalities : 

- Be able to "flag" easily the DEV Model thanks to an icon or color to inform/alert users if they are on DEV or PROD Model

- User not Page Builder should not see the Edit Page mode but only the Preview. It could be interesting also to be able to choose which user can use the Preview function

- We need to be able to take offline an APP same as for Model

- Having the option "multiple source model" when duplicating a page to add/remove sources

- Be able to publish all pages updates at the same time with one button in case of big ALM