Fix options not being passed to taskConfig

When using the task with a non-standard key location, the options never were passed to the task config, as the options were removed due to multiTask files normalization, resulting in an error
```console
Fatal error: Unable to locate your private key.
```
if one changed the `options.privateKey` property.
This was never found out, because the tests itself use the internal method `extensionHelper.createObject` and passed the `options` in. The code in `tasks/crx.js` was never part of the tests.

This PR fixes this, by properly passing on the `options` hash to the taskConfig if defined. As a side-effect it also adds coverage for `tasks/crx.js`.