Component key that finds the keys of plugins matching a given key

Usage:

        # get a sorted list of the keys to all 'foo.bar' plugins
        pluginNames = binding.Obtain( binding.PluginKeys('foo.bar') )

        # get an unsorted list of the keys to all 'foo.bar' plugins
        pluginNames = binding.Obtain(
            binding.PluginKeys('foo.bar', sortBy=None)
        )

sortBy is either a false value or a callable that will be applied to each key to get a value for sorting purposes. If set to a false value, the keys will be in the same order as yielded by config.iterKeys(). sortBy defaults to str, which means the keys will be sorted based on their string form.

__init__ (
        self,
        configKey,
        sortBy=str,
        )

findComponent (
        self,
        component,
        default=NOT_GIVEN,
        )