Add delay for snapshots

[Martyfree123]

Hello! Right now, the plugin takes a snapshot right as the print finishes, but this doesn't give enough time for my toolhead to move to the "park" position out of view.

Here is what it currently captures:

Here's what I'd like it to capture: This is only a few seconds later as the toolhead moves the the park position in the upper right-hand corner.

I think a good solution is just adding an option for "Snapshot Delay", and the user can input a delay in seconds. Then the plugin will wait that amount of time, grab the snapshot, and send the message as normal.