Custom emoji buttons missing from work items

When opening emoji pickers, either reactions to the work item or a note, the button to create a custom emoji never appears.

Backend implementation

In legacy issues, we passed new_custom_emoji_path from the backed as a Haml data attribute. However, we need to expose this path via GraphQL so the frontend can get this path for different work item drawers which can have group-level and project-level contexts

Acceptance criteria

• Button appears when user has permissions (Developer role in work item's parent group)
• Button points to work item's parent group new emoji page regardless of context (i.e. if in an epic in group A, with issue open in drawer in group B, must tie to group B)