[Tock Studio] Ubiquitous test component

[rkuffer]

New component for testing dialogs from anywhere in the studio:

• Addition of a button in the application header to open a test dialog in a modal window
• Add a button in different views to open the modal and launch a discussion with the sentence provided:
  • Language understanding > Inbox sentences
  • Language understanding > Search sentences
  • Stories& answers > Faqs
  • Analytics > Dialogs
  • Analytics > Users
  • Story details modal

Initial locale and configuration are automatically set if supplied.

Also added : the ability to put carriage returns in user message.

The historical test view remains unchanged except for the ability to enter carriage returns.