Feature: set the log level for crashes

[ftrotter]

Not every report crashing is a critical error. But some definitely are.

It is useful to be able to set the slack logging for a Laravel instance to "critical"... and out of the box, SQL errors in reports will generate an "error" level log, and not cause the slack logging to be invoked...

but then for central reports, the ones that I am expecting to be used and reliable every day... when they crash, I would like to get a slack... and not when less important reports crash..

I am following these instructions for the slack logging setup, except I have set the level to "error" rather than critical, which means I get a notice anytime ANY report crashes... which is not really useful, as I am constantly developing reports and they tend to crash until they do not crash, when I am initially designing them.