Fixes#27189
When an inbound message is debounced, the Bot Framework turn context is
revoked before the debouncer flushes and the reply is dispatched. Any
attempt to use the revoked context proxy throws a TypeError, causing the
reply to fail silently.
This commit fixes the issue by adding a fallback to proactive messaging
when the turn context is revoked:
- `isRevokedProxyError()`: New error utility to reliably detect when a
proxy has been revoked.
- `reply-dispatcher.ts`: `sendTypingIndicator` now catches revoked proxy
errors and falls back to sending the typing indicator via
`adapter.continueConversation`.
- `messenger.ts`: `sendMSTeamsMessages` now catches revoked proxy errors
when `replyStyle` is `thread` and falls back to proactive messaging.
This ensures that replies are delivered reliably even when the inbound
message was debounced, resolving the core issue where the bot appeared
to ignore messages.
