Tidy up markdown toolbar handling across all editors

Any editor for the markdown mode will now automatically get
the markdown toolbar added.

The comment node has been updated to handle this properly and
to not add two copies of its content to the sidebar.

packages/node_modules/@node-red/nodes/locales/en-US/messages.json

@@ -307,12 +307,7 @@
         }
     },
     "comment": {
-        "comment": "comment",
-        "label": {
-            "title": "Title",
-            "body": "Body"
-        },
-        "tip": "Tip: The body text can be styled as <a href=\"https://help.github.com/articles/markdown-basics/\" target=\"_blank\">GitHub flavoured Markdown</a>"
+        "comment": "comment"
     },
     "unknown": {
         "label": {

packages/node_modules/@node-red/nodes/locales/ja/messages.json

@@ -307,12 +307,7 @@
         }
     },
     "comment": {
-        "comment": "comment",
-        "label": {
-            "title": "タイトル",
-            "body": "本文"
-        },
-        "tip": "注釈: 本文は<a href=\"https://help.github.com/articles/markdown-basics/\" target=\"_blank\">GitHubのMarkdown形式</a>として整形されます。"
+        "comment": "comment"
     },
     "unknown": {
         "label": {

packages/node_modules/@node-red/nodes/locales/zh-CN/messages.json

@@ -297,11 +297,6 @@
         }
     },
     "comment": {
-        "label": {
-            "title": "标题",
-            "body": "主体"
-        },
-        "tip": "提示: 主题内容可被格式化为 <a href=\"https://help.github.com/articles/markdown-basics/\" target=\"_blank\">GitHub风格的Markdown</a>"
     },
     "unknown": {
         "label": {