Icons > Add a deprecated folder to help the monitoring and compatibility between the platform versions

There is no way today to check quickly in the sources if an icon is deprecated or not.
It is touchy to remove an icon from the platform: even if we don't use it in the main bundles, we never know if the icon is not used in a marketplace or custom bundle.

One solution:

• add a deprecated folder in the icon managers packages (nuxeo-jsf/nuxeo-platform-webapp-base and nuxeo-dm/nuxeo-platform-webapp for now).
• in each deprecated folder, add 2 folders: one for the latest release version, one for the following, see the following example:

- icons
  - deprecated
    - 5.6
    - 5.7

For the next 5.7 release, the 5.6 folder will be deleted and a 5.8 folder will be created. That way, we keep the deprecated icons during a version, and we can list all the icons in the upgrade note.

Another solution would be to have a backward compatibility bundle for each release, to add only when you notice that some icons are missing in your project.