Currently packageFiles callbacks take 2 parameters, $context and $config.
This patch allows for specifying an extra parameter in the packageFiles
definition that will be passed to the callback. Example:
'callback' => function ( $context, $config, $extra ) { ... },
'callbackParam => [ 'this is val 1', 'this is val 2' ],
The callback will be called with the usual $context and $config
parameters, and the extra array is passed as third parameter.
Bug: T233634
Change-Id: Ie11874665f4f9a557d4e394dcab3a972887e8126
e35f53316c