erp5_workflow: add list field to show transition variable in interaction view, which should have been there.

erp5_workflow: add Embedded File as allowed and hidden content type to Configuration Workflow, because it should have been.

Worklist.py: causality state getter returns an empty string instead of None when it is not definded.

ERP5TypeTestCase.py: install erp5_workflow template after finish erp5_base installation to not crash SQL initiation.

ERP5TypeTestCase.py: move dynamicalWorkflowConvertion to the end of Site creation, so the speed grains a great improvement.

Merge branch 'erp5_workflow_converted' of https://lab.nexedi.cn/Wenjie/erp5_workflow into erp5_workflow_converted

erp5_workflow: rename getRoleList to getManagedRoleList in interaction view and script PermissionRoles_asCellRange.

WorkflowTool.py: when convert interactions, the interaction contained script can only be script, it is no necessary to consider these script could be another interaction.