Harmonize WorkflowResult attachments handling in attachment commands

Current situation

A workflow execution produces two WorkflowResult type attachments: execution log and allure report. These attachments have no UUID and currently, they are retrieved using the pattern {workflow_uuid}+'_a'/'_e' depending on the attachment type. Soon, two new WorkflowResult attachments (execution reports) will be created at the end of the workflow execution, adding to the complexity if we want to handle these attachments in the same way.

Desired outcome

Find a clean way to handle WorkflowResult attachments in attachments commands.