Allow maintainers to edit comments in work item epics

In legacy epics, a user with Owner or Maintainer access can edit non-authored comments but this is not enabled for work item epics.

# ee/app/policies/epic_policy.rb

rule { can?(:owner_access) | can?(:maintainer_access) }.enable :admin_note

Proposal

Add permissions for work items at the group level to allow owners and maintainers to edit any comment in a work item