Automate generation of ADDITIONAL-LICENSES.yml files during frontend builds

Since 13.0 the code base contains ADDITIONAL-LICENSES.yml files in the src/main/resources/META-INF folder of frontend modules. These files cover the licenses of frontend files (JavaScript, CSS, etc.) packaged in the generated JAR file.

Some examples:

• CMS API: https://code.onehippo.org/cms-community-dev/hippo-cms/blob/release/13.0/api/src/main/resources/META-INF/ADDITIONAL-LICENSES.yml
• CMS login: https://code.onehippo.org/cms-community-dev/hippo-cms/blob/release/13.0/login/src/main/resources/META-INF/ADDITIONAL-LICENSES.yml
• Channel Manager: https://code.onehippo.org/cms-community-dev/hippo-addon-channel-manager/blob/release/13.0/frontend-ng/src/main/resources/META-INF/ADDITIONAL-LICENSES.yml

These ADDITIONAL-LICENSES.yml files are generated by a custom script written by jdegooijer (attached in CMS-11733).

The license files need to stay in sync with the package.json files: whenever a dependency is changed, updated, added or remove the license file needs to be updated too. Currently that's a manual process, and requires the use of a custom, undocumented script.

We should change all frontend build to generate the ADDITIONAL-LICENSES.yml files automatically, as part of the build. That way we'll be sure that these files stay in sync with the actual packaged dependencies.