Merge branch '466082-change-epic-work-item-path-from-work_items-to-epics' into 'master'

Added epics to work items route

See merge request https://gitlab.com/gitlab-org/gitlab/-/merge_requests/155773



Merged-by: Eugenia Grieff <egrieff@gitlab.com>
Approved-by: Deepika Guliani <dguliani@gitlab.com>
Approved-by: Eugenia Grieff <egrieff@gitlab.com>
Reviewed-by: Alexandru Croitor <acroitor@gitlab.com>
Reviewed-by: Nicolas Dular <ndular@gitlab.com>
Reviewed-by: Deepika Guliani <dguliani@gitlab.com>
Co-authored-by: Nicolas Dular <ndular@gitlab.com>
Co-authored-by: Donald Cook <dcook@gitlab.com>