Manual lookup should have a "send to channel" button

[barend]

This is semi related to #5. Whenever plates are not found on an interesting car, there's probably more than one person who does a manual lookup.

If you manually look up a tag by the chat command /car XJ-228-X, the lookup result is sent to the person who did the lookup. It'd be useful if this result includes a "post to channel" button, giving the user the option of re-posting it publicly in the channel.

Bonus points if it prevents posting the same tag multiple times in a short timespan.