Authority TOC generation

[abartov]

Where an authority does not have a root collection defined, a default, transient TOC tree should be generated (and cached).

The tree should be composed of every Manifestation the authority is involved in, in any role, and those Manifestations should be grouped by Collection (and sub-collection, if one exists).

If an authority is involved with only one/some of the Manifestations in a Collection, include only those (and title the heading accordingly, i.e. "out of [volume X title]", rather than "[volume X title]".

This generated tree is also used to create permanent root collections, and to augment existing ones. (i.e. if an authority has a root collection, and new texts are uploaded that involve this authority, but did not already exist as placeholders in one of the root collection's collections, those new texts should be automatically added to the root collection under appropriate collections as described above.

(texts uploaded as volume-less should be added into [a newly-created, if missing] "uncollected works" collection under the root collection.)

[abartov]

@damisul - I'd like you to start thinking about the data model and queries needed to accommodate this logic.