Handled empty attribution section on member detail page

refs https://github.com/TryGhost/Team/issues/1986

- hides attribution section if there is no source and page/post attribution

ghost/admin/app/components/gh-member-details.hbs

@@ -64,7 +64,7 @@
                     {{/if}}
                 </p>
             </div>
-            {{#if (and (feature 'sourceAttribution') @member.attribution)}}
+            {{#if (and (feature 'sourceAttribution') this.showAttribution)}}
                 <div class="gh-member-details-attribution">
                     <h4 class="gh-main-section-header small bn">Attribution</h4>
                     {{#if this.referrerSource}}

ghost/admin/app/components/gh-member-details.js

@@ -7,4 +7,8 @@ export default class extends Component {
     get referrerSource() {
         return this.args.member.get('attribution')?.referrer_source;
     }
+
+    get showAttribution() {
+        return this.referrerSource || (this.args.member?.attribution?.url && this.args.member?.attribution?.title);
+    }
 }