Annotated List Seeds: Extend list seeds to allow extra annotations

[cdrini]

Subtask of #6718

• First just add option for notes and have it apply to all existing lists. This infrastructure will be used to support things like position/primary/etc (Lists: Adding notes to seed #6160)
• We will likely need a wrapping object structure like:

seeds:
- { position: 1, item: { key: OL1W }, primary: true }
- { position: 2, item: { key: OL2W }, primary: true }
- { position: 0, item: { key: OL1513W }, primary: false }
- { position: 8, item: { key: OL1513W }, primary: false }
- { position: '1-7', item: { key: OL12W }, compendium: true }

to be consistent with the way references work in infogami. But of course we will have to maintain backwards compatibility with un-annotated seeds.