Better logging during wopi info parsing,
especially upon failures.
Refactored the code from Storage.cpp into
JsonUtil.hpp.
Minor optimizations.
Add unit-tests for the parsing logic.
Change-Id: Ifebc3f6b7030a6c7b3b399786633f6b5e8737478
Reviewed-on: https://gerrit.libreoffice.org/49927
Reviewed-by: Ashod Nakashian <ashnakash@gmail.com>
Tested-by: Ashod Nakashian <ashnakash@gmail.com>