Include optional addons' version alignement in the release process

Optional addons must not be automatically released while releasing the platform, so they're currently simply ignored.
An improvement would be to partially include them in the process:

• do not release them (no tag, nor build),
• they must not be able to break the release,
• update their POMs to keep their versions up-to-date with the platform.

That would help to early discover regression, deprecation, breakage, ... on those addons.