Copilots can still edit to assign to themselves

[jmgasper]

REF: https://topcoder.atlassian.net/browse/PROD-4379

We need to ensure that a copilot can't:

• Create a task assigned to a different member
• Activate the task
• Re-assign the task to themselves
• Close it

We're seeing this still possible:

https://github.com/topcoder-platform/work-manager/assets/21790/26dc8f29-53b0-4089-807e-27b92b3bbaf1

[suppermancool]

@jmgasper done in work-manager-issue-1578.patch (this patch against commit 8f0e2ce262e2401f46fd1e4fbedfc95b16d072f6 in develop branch)