[WIP] Migrate to the NamedGraphs v0.14 interface

[mtfishman]

Summary

NamedGraphs v0.14 replaced the position-graph interface with encode and decode, and removed the submodules DataGraphs imported from, so main cannot load against it at all. Also clears the five method ambiguities the migration surfaced, turns on the Aqua check guarding them, and fixes two bugs in quotient_graph over a PartitionedView.

TODO

• Remove the [sources] pin on NamedGraphs main and confirm [compat] admits the registered version, once NamedGraphs 0.14 registers.
• Add a changelog recording the breaking changes, including the ones inherited through NamedGraphs: vertices now returns Dictionaries.Indices in insertion order, edges is a lazy iterator, and the mutating functions return Bool.
• Documentation pass: the package has one docstring and no doctests.