Work items list - issues list parity

This issue captures the work required for the group-level work items list to reach parity with the issues list.

UX work:

• Make empty states more general instead of epic-specific

backend work:

• Add type to NegatedWorkItemFilterInput so user can do Type != Issue filtering on UI
• Add missing EE filters (Epic, Health, Iteration, Weight), also update workItemStateCounts
• Add missing CE filters (Release, Contact, Organisation), also update workItemStateCounts
• Add Created date, Closed date filters and update workItemStateCounts? This is behind feature flag issue_date_filter
• Add missing bulk edit arguments (Status, Assignee, Epic, Milestone, Iteration, Health status, Subscriptions, Confidentiality, Move)
• Add missing fields for UI cards (blockingCount, hidden, humanTimeEstimate, mergeRequestsCount, moved, taskCompletionStatus) (#417148 (closed))
• Add missing sort options (in order of importance: Priority, Manual, Popularity, Closed date, Milestone due date, Label priority, Health, Weight, Blocking)
• Add manual ordering
• Add import/export CSV
• Add import Jira
• Add "Email a new issue to this group"
• Add subscribe to calendar/RSS

frontend work:

• Add Epic, Health, Iteration, Weight search filters
• Add Release, Contact, Organisation filters
• Add Created date, Closed date filters
• Make empty states more general instead of epic-specific
• Add Status, Assignee, Epic, Milestone, Iteration, Health status, Subscriptions, Confidentiality, Move to bulk edit sidebar
• Add blockingCount, hidden, humanTimeEstimate, mergeRequestsCount, moved, taskCompletionStatus to UI cards
• Add Priority, Closed date, Milestone due date, Popularity, Label priority, Manual, Health, Weight, Blocking sort options
• Add import/export CSV
• Add missing filters for export CSV (#499314 (closed))
• Add import Jira
• Add "Email a new issue to this group"
• Add subscribe to calendar/RSS