Counterpart for LlStgsysAppend: Split preview files

The storage API is missing a counterpart to LlStgsysAppend. Please add a LlStgsysSplit function that extracts a page- or job index range to a new preview file. This would make the storage API complete and you would be able to freely rearrange the contents of preview files.

We’ll introduce an extension to the LlStgsysConvert-API in LL24 that will allow to extract page or job ranges. You’ll also be able to delete single pages and jobs from a preview file.