LPS-42694 last publish page versioning

Hi @matethurzo,

seems that last publish date wasn't working when page versioning is enabled. This is caused by not storing the last-publish-date in LayoutSetBranch settings.

I had to change some lines in LayoutStagingHandler because in that cases the serviceContext.isSignedIn was false. Not sure if this can be done in a better way.

Thanks!

@KocsisDaniel