Design model for annotation sessions in solid pods

[alastair]

In the CE, we store annotation sessions as an ItemList. In solid we use an ldp:container, which is approximately equal to a "folder" in solid.

The annotation tools that we have currently just save all annotations to a current folder, but we should eventually introduce the concept of an annotation session - user + toolkit + source material + list of annotations in solid too, so that we don't have to load/parse too many items. Annotations may be able to exist in many container or sessions at once, we need to decide how to handle this (how to sync all when one is changed)

It'd also be nice to be able to load all annotations for a session in a single http query (or fewer than 1 query per annotation file). This could be achieved by inlining annotations in the ldp:container (but comes with its own considerations regarding annotation ids), or look at something like the ldp paging api