Add exceptionToString() and getCaughtExceptionAsString() methods in
tools.

Use the new methods in DbgUnhandledException()

Add special-case case code for most of the exceptions that contain extra
fields, so all of the relevant data ends up in the log

Change-Id: I376f6549b4d7bd480202f8bff17a454657c75ece
Reviewed-on: https://gerrit.libreoffice.org/67857
Tested-by: Jenkins
Reviewed-by: Noel Grandin <noel.grandin@collabora.co.uk>