A time_zone represents a timezone identified by its IANA ID. This
allows for a straightforward conversion to QTimeZone.
[ChangeLog][QtCore][QTimeZone] QTimeZone can now be constructed
from a std::chrono::time_zone pointer.
Change-Id: I093d9fc2e989475d30730a9dcdef491903a2aeb2
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>