Add option to the NotificationHandler and option to extend the msg

[gs202]

Add an option to send additional data in the notification besides the log msg (e.g. custom msg)
example:

msg = "Something is broken"
log.error("can't find parameter")

notification:

Something is broken
can't find parameter

[liiight]

Not sure I get the use case

[gs202]

To enrich the log message, I'd like to have more information added on top of the log message when sending the notification.
I.e, if the log message is: "can't find parameter",
My extra message is: "Something is broken, "
The notification will be ""Something is broken, can't find parameter"

[liiight]

Looking into this now. Seems it would be kinda tricky to define this in a generic way, since each developer has different body. Would you add it to email subject? To push notification as a prefix/suffix? Seems like this should be handled by the notification sender

[breezko]

I'd llike to get my hands dirty on it,
so what is the expected result? @liiight