enhance(v2ex): add content, member, created, node fields to topic output (#648)

- Add content field to display topic body text
- Add member field to show topic author
- Add created field to show topic creation timestamp
- Add node field to show topic category
- Add id field for consistency with hot/latest commands

This makes v2ex topic command return meaningful details that are
not available in hot/latest listings.

Author: reabiter

src/clis/v2ex/topic.yaml

@@ -19,10 +19,15 @@ pipeline:
         id: ${{ args.id }}
 
   - map:
+      id: ${{ item.id }}
       title: ${{ item.title }}
+      content: ${{ item.content }}
+      member: ${{ item.member.username }}
+      created: ${{ item.created }}
+      node: ${{ item.node.title }}
       replies: ${{ item.replies }}
       url: ${{ item.url }}
 
   - limit: 1
 
-columns: [title, replies, url]
+columns: [id, title, content, member, created, node, replies, url]