This epic splits out the ~backend work of adding Custom Emoji at group level. If all these components are complete, Custom Emoji will be functional as a MVP. There is additional ~frontend work needed to improve the user experience. Check out https://gitlab.com/groups/gitlab-org/-/epics/1820 for the other pieces of that puzzle. ### Goal * A user can add custom emoji * A user can use custom emoji in description or comment * Custom emoji get rendered in those messages