(I am collecting here a few topics since we already have a PR ready that covers them all and it's quicker to have a single issue)

Some issues and limits of shape placement:

• It's possible to define tabs in placements. However, the way tabs are "written" to the html output is hardcoded. It should support alternates.
• Tab names can't have whitespace in them: it won't be displayed as such. Alternates allow fixing that as needed, without having to worry about finding a general solution right now that also will not break anyone's code and hacks.
• Within a tab, there is no way to further "group" shapes. Bootstrap does that with cards. Cards should allow alternates as well, and in general behave similarly to tabs (in terms of setting them up for and using them in pages and editor views)

In our PR we will add cards to placement, handled in a similar way as tabs. Both tabs and cards are "generated" using shapes, so we can create alternates of them.
We update the "Edit Placement" functionality of ContentTypes to handle both for editor views.

(cc: @HermesSbicego-Laser who has come up with the feature and developed it)