Including full stack trace in log messages

[oxinabox]

I but basic code for this in
JuliaLang/julia#48282 (comment)

It would be nice to make a better version of this either as an example of a TransformerLogger or as a predefined TransformerLogger.

A thing we could probably make as a side effect of implementing this is a LogStacktrace() object.
Which could also be used manually as a @info "hi" stacktrace=LogStacktrace() and which gives a good pretty printed stacktrace.
The Stacktrace transformer logger work just insert that argument automatically everywhere. (And combined with filters would insert it only in correct places)