Respond in thread

For some commands, especially any that may output a large amount of text, responding to the message in thread, instead of in the main channel might be a better experience.

- Create a function that determines where to send the response based on the event so it can be reused.
- If the message came from a thread, respond in that thread.
- If the message _did not_ come from a thread, respond in the thread for that message.
- Apply this to the `ping` and `jobs` commands.