Expose contacts_available field for work item CRM contacts widget

What does this MR do and why?

Expose contacts_available field for work item CRM contacts widget

This will allow us to determine whether to show the CRM contacts widget in the frontend

Related to #525875 (closed)

References

Screenshots or screen recordings

How to set up and validate locally

1. Create a contact and a work item in a group
2. Ensure the field returns true for the work item
3. Create a work item in a group with no contacts
4. Ensure the field returns false for the work item

{
  projects {
    nodes {
      name
      workItems {
        nodes {
          widgets {
            ... on WorkItemWidgetCrmContacts {
              contactsAvailable
              contacts {
                nodes {
                  firstName
                }
              }
            }
          }
        }
      }
    }
  }
}

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