Ability to customize the deferReply message

[ByronBecker]

To provide a better user experience for my bot users, I'd like to be able to customize the deferred response experience of my bot's users when computing a response to a user's command could take at least 2-4 seconds to complete and then reply back to the user (i.e. more than the 3 second limit at times).

My current solution is to first reply to the user with a personalized message (I cycle through a random reply string out of 10 possible strings each time the user sends a command), and then once my async process is completed edit the original reply message.

While this solution works, the initial reply text UI in the frontend gives the user a "final" reply UX, whereas the deferred reply three dot animation signals to the user the deferred response UX, but has the same "Bot is thinking" text each time it is used.

Ideally, deferReply would take a content or message field of type string, and then respond with that custom text to the user while waiting for the followUp response.