Include addable types constraints in plone.restapi

[tisto]

Right now there is no way for a client to tell which content types are addable in a certain context (or globally).

The "types" endpoint just lists all existing content types, a first step would be to include the global_allow attribute there.

Though, we still need to include the information which content types are addable in a certain context. This would need to be embedded in the regular content response I guess.

Problem is we need to somehow solve the actions/framing API design in order to properly implement this.

[jaroel]

• add 'addable' to type info, based on context.getAllowedTypes. Same as the add menu.
• allow @types on all context.