add a noAction() method to Object and FileWriter to return the noaction flag value

Also update Process to use this new method.

The rationale of this pull request is to provide a uniform way of retrieving the noaction flag value, whether the object is based on CAF::Object or CAF::FileWriter (which is not a CAF::Object).

A typical use case is demonstrated in `ncm-named` (https://github.com/quattor/configuration-modules-core/pull/243) to avoid printing an error message in unit tests when a file was not updated because of the noaction flag defined in the tests..