Allow rendering Bot Framework WebChat without DirectLine connection

Feature Request.

Is your feature request related to a problem? Please describe.

I am using the ReactWebChat component in a 'transcript viewer' scenario, where no interactivity is allowed. Unfortunately it is required to pass directLine, passing an empty object ({}) will work but throw an javascript error.

<ReactWebChat 
             directLine={{}}

TypeError: Cannot read property 'subscribe' of undefined
    at subscribeToPromiseQueue (<anonymous>:75216:33)
    at connectionStatusToNotification$ (<anonymous>:75235:35)
    at tryCatch (<anonymous>:223445:17)
    at Generator.invoke [as _invoke] (<anonymous>:223662:22)
    at Generator.next (<anonymous>:223498:21)
    at next (<anonymous>:4057:29)
    at proc (<anonymous>:4008:3)
    at <anonymous>:3487:17
    at immediately (<anonymous>:2970:12)
    at runForkEffect (<anonymous>:3486:3)

Describe the suggestion or request in detail

A way to use the ReactWebChat component in an offline / no interactivity scenario.

Describe alternatives you have considered

Passing a mock DirectLine client / RXJS Observable. However, it seems that I did need to use RXJS for this, which add a lot of overhead to my project.
If there is a way to add a simple mock object to disable the connection, that would be feasible for me as well.

Additional context

See https://github.com/iMicknl/powerbi-botframework-chat-transcripts/issues/9.

Similar request: https://github.com/microsoft/BotFramework-WebChat/issues/3032

Similar customer request: https://github.com/microsoft/BotFramework-WebChat/issues/4037

[feature-request]

Start at the ReactWebChat component and trace where the required directLine connection causes the reported empty-object failure. Define and verify an offline, transcript-only rendering path without a DirectLine connection; done means the component renders without interactivity while the existing connected path remains usable.