Add Pre* Tasks for various stages in Deployer

[MarcBastienTTA]

When running Deployer, it may be necessary or at least useful, if some additional, customer specific tasks could be excuted. This is already possible in step 70 (“Deploy Cloud Pak assets” / cp4d_asset), but would be necessary for other steps as well.

For a specfic customer situation: we need the define namespace in a very special way, and would like to include an ansible task to do this before the actual installation starts.

Thanks.