[context] use private / internal knowledge source for AI answers

Problem: issue is the need to make all content public, for both knowledge centre and 3rd party sources. For some of the use cases were want to use, privacy issues prevents us from using it. The inability to nominate multiple sources would be another nice to have.

Consequence: We see a lot of potential with Front AI Answers but are currently looking at other solutions to solve these issues outside of it.

Request: Add multiple sources at once for AI answers for chat, including non public ones. Particularly important for cases where of internal chatbots.