Add path to "download complete" notification body

[aroberts]

I didn't see a response to #978 so I tried to just follow what was there. This PR adds download path to the notification body as a newline-separated field.

[aroberts]

@Tzahi12345 any chance you could look at this sometime? The use case here is using the notification system as a jump-off for automation. By providing access to the filename, a user can invoke a web hook that kicks off other processes once the file is completed (beyond just communication).

[aroberts]

any chance I can get a quick look at this? @Tzahi12345 @martadinata666