Configuration support for all drivers.
This module allows support for setting configurations either from default or from a particular FLAGS group, to be able to set multiple configurations for a given set of values.
For instance, two lvm configurations can be set by naming them in groups as
[lvm1] volume_group=lvm-group-1 ...
[lvm2] volume_group=lvm-group-2 ...
And the configuration group name will be passed in so that all calls to configuration.volume_group within that instance will be mapped to the proper named group.
This class also ensures the implementation’s configuration is grafted into the option group. This is due to the way cfg works. All cfg options must be defined and registered in the group in which they are used.