Apply fixed conversation flow mode to Chat Widget of MVP

[turnerrainer]

AS A Product Owner
I WANT chatbot conversations to be both text- and fixed conversation flow-based
SO THAT I could apply them both according to what's most suitable in given situation

Acceptance Criteria

• Chat Widget displays optional selections for End User to choose from
• End User can press on the button of choice
• When in fixed conversation flow mode, the End User can not send any text
• Conversations can be either text- or fixed conversation flow-based depending on how they have been defined in the back-end (Rasa + Ruuter DSLs)

DSL

• Define JSON schema for chats in conversation flow mode

GUI

• Apply buttons based on JSON input from the backend
• Button values must be translatable i18n values

[baha-a]

PR:

• Handle Rasa buttons #12

[turnerrainer]

Back-end finished by @baha-a
@bartekpospiech will take over the GUI part

[KlviG]

Done, exept GUI part, due to prio changes