Configurable user-interaction patterns, optional full decoupling from chat interface

[nilspalumbo]

• Simplify building non-chat applications.
• Make the degree of user interaction requested configurable; similarly, make it easier to control which output is seen by the user (for example, it should be easy to have the user interact with only the root task).
• Make it simple for an application to request user input only when specifically requested by an agent (i.e. generalizing the recipient pattern)
• Similarly, allow requesting user input periodically
• Users should be able to interrupt execution and send a message at any point