Ui improvements (#5948)

* PLT-5849 - Code block wrap on IOS

* PLT-5972 - Comment has first line indented

* PLT-6048 - Adjusting UI for link previews

* PLT-5733 - Adding error text theme option

webapp/components/user_settings/custom_theme_chooser.jsx

@@ -83,6 +83,10 @@ const messages = defineMessages({
         id: 'user.settings.custom_theme.buttonColor',
         defaultMessage: 'Button Text'
     },
+    errorTextColor: {
+        id: 'user.settings.custom_theme.errorTextColor',
+        defaultMessage: 'Error Text Color'
+    },
     mentionHighlightBg: {
         id: 'user.settings.custom_theme.mentionHighlightBg',
         defaultMessage: 'Mention Highlight BG'