Workflow, add popup listing users who can do a task. #11012

The popup is shown in the block, and in the workflow overview, to list
who can do the currently active task.

The users are listed with their email addresses (or whatever is
configured in the show user details setting in the Moodle admin
screens.)
Fix use of old generator base class name. #11290
Workflow: Display "Show names(N)" on each step, #11314
Changing workflow language strings to comply with Moodle, #11760
Behat tests for block-workflow, with 2.7 fixes. #11822
Fix failing workflow unit tests. #11981