[Backport 14.6] Add flags to /versions which version is 'active' from the HST pov and which version corresponds to the published variant

To be able to support the right colors in the CM which version is active and whether it is live or not, we need:

1. on /versions root level an extra boolean whether the document is published or not
2. per version an extra flag which indicates whether the version corresponds to the published version (1 version corresponds to the live version ). Note that this also must work for branches! It is fairly easy, since in version history we keep a label per version which corresponds to the published version for that branch. Note only one version can have publishedVersion = true
3. per version an extra flag which indicates whether that version is at this moment the active one served by the HST. There can only be one version with this active = true flag. Active is true does not mean the document has to have a published version: if there is no published version, active will still be true: it would be the active version if the document would get published