bioghist: banish <chronlist>

As proposed by Dan in ticket 5094, this eliminates AtoM's complex `<chronlist>` field when exporting EAD in favour of a simplified, more standard pair of non-nested `<bioghist>` and `<origination>` fields.

TODO:

- [ ] Add a `@role` attribute to `<geogname>` elements in the event that they've been added in the events module, to distinguish from regular place access points