workflows: template renaming

* Renames the template hp_details to hp_details_base in preparation
  of better template structure.

Reviewed-by: Jan Aage Lavik <jan.age.lavik@cern.ch>
Signed-off-by: Georgios Papoutsakis <georgios.papoutsakis@cern.ch>
wworkflows: template fixes

* Adds new block workflow_completed to hp_details_base template.

* Adds template hp_details to extend from hp_details_base.

Reviewed-by: Jan Aage Lavik <jan.age.lavik@cern.ch>
Signed-off-by: Georgios Papoutsakis <georgios.papoutsakis@cern.ch>