Koenig - Fixed jump-to-top bug when focusing editor

refs https://github.com/TryGhost/Ghost/issues/9311
- the editor was being focused and the cursor placed properly but the act of focusing also reset the scroll position
- pulled the `.gh-koenig-editor` class into the component rather than leaving it in the template so that the component has access to `this.element`
- ensure the `.gh-koenig-editor` container is scrolled all the way to the bottom after focusing the editor

ghost/admin/app/components/gh-koenig-editor.js

@@ -3,7 +3,7 @@ import Component from '@ember/component';
 export default Component.extend({
 
     // public attrs
-    tagName: '',
+    classNames: ['gh-koenig-editor'],
     title: '',
     titlePlaceholder: '',
     body: null,
@@ -35,6 +35,9 @@ export default Component.extend({
                 this._editor.run((postEditor) => {
                     postEditor.setRange(range.tail.section.tailPosition());
                 });
+
+                // ensure we're scrolled to the bottom
+                this.element.scrollTop = this.element.scrollHeight;
             }
         },
 

ghost/admin/app/templates/components/gh-koenig-editor.hbs

@@ -1,25 +1,22 @@
-{{!-- scrollable container --}}
-<div class="gh-koenig-editor">
-    {{!-- full height content pane --}}
-    <div class="gh-koenig-editor-pane" onclick={{action "focusEditor"}}>
-        {{gh-textarea title
-            class="gh-editor-title"
-            placeholder=titlePlaceholder
-            tabindex="1"
-            autoExpand=".gh-koenig-editor"
-            update=(action "onTitleChange")
-            focusOut=(action "onTitleFocusOut")
-            keyDown=(action "onTitleKeydown")
-            didCreateTextarea=(action "onTitleCreated")
-        }}
+{{!-- full height content pane --}}
+<div class="gh-koenig-editor-pane" onclick={{action "focusEditor"}}>
+    {{gh-textarea title
+        class="gh-editor-title"
+        placeholder=titlePlaceholder
+        tabindex="1"
+        autoExpand=".gh-koenig-editor"
+        update=(action "onTitleChange")
+        focusOut=(action "onTitleFocusOut")
+        keyDown=(action "onTitleKeydown")
+        didCreateTextarea=(action "onTitleCreated")
+    }}
 
-        {{koenig-editor
-            mobiledoc=body
-            placeholder=bodyPlaceholder
-            autofocus=bodyAutofocus
-            spellcheck=true
-            onChange=(action "onBodyChange")
-            didCreateEditor=(action "onEditorCreated")
-        }}
-    </div>
+    {{koenig-editor
+        mobiledoc=body
+        placeholder=bodyPlaceholder
+        autofocus=bodyAutofocus
+        spellcheck=true
+        onChange=(action "onBodyChange")
+        didCreateEditor=(action "onEditorCreated")
+    }}
 </div>