The latest XDG spec (0.8) defines XDG_STATE_HOME that does not exist
in QStandardPaths::StandardLocation.
Some Linux distributions clean XDG_CACHE_HOME on restart which makes
XDG_STATE_HOME useful as a path for saving application state.
This commit adds StateLocation and GenericStateLocation to serve as a
StandardLocation for XDG_STATE_HOME for all platforms.
This commit also updates docs and tests to fit the new changes.
[ChangeLog][QStandardPaths] Added StateLocation &
GenericStateLocation to StandardLocation
Change-Id: I470602466c37f085062cc64d15ea243711728fa5
Reviewed-by: David Faure <david.faure@kdab.com>
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>