Updated frontend dependencies

In the Frontend Workspace the frontend-maven-plugin downloads and uses Yarn version 1.22.4 when it is built. The frontend dependencies, have been updated to the latest versions and node.js to latest LTS version 12.16.1.

Follow Section, “Updated frontend dependencies” for upgrade information.

(CMS-17050)

Changed the behavior of cm.UNDEFINED on template side

The value of cm.UNDEFINED (e.g. provided by the corresponding Freemarker macro) is now treated in a special way on template side, so various build-ins like ?has_content and ?length now produce a more reasonable result when used in conjunction with cm.UNDEFINED .

Follow Section, “Changed the behavior of cm.UNDEFINED on template side” for upgrade information.

(CMS-14250)

Configuration for "titleKey" in brick "preview" changed from "preview_label_DEFAULT" to "preview_label_default"

There was a misalignment in the brick "preview" that made the default localization for titleKey="preview_label_default" useless (one time lower case "default", one time upper case "DEFAULT").

Follow Section, “Configuration for "titleKey" in brick "preview" changed from "preview_label_DEFAULT" to "preview_label_default"” for upgrade information.

(CMS-17150)

Removed "includeGutter" parameter from "aspect-ratio-box" utility mixin

The "includeGutter" parameter got removed from the "aspect-ratio-box" utility mixin. Please handle this otherwise, if you need this.

(CMS-9886)