Refactored code common to all core classes

[IsaacFigNewton]

I created 2 interfaces with code shared across the different core Hypergraph classes. Below is a Mermaid diagram indicating the inheritance hierarchy.

classDiagram
    class IHypergraph
    class DirectedHypergraph
    class IUndirectedHypergraph
    class Hypergraph
    class MultiplexHypergraph
    class TemporalHypergraph

    IHypergraph <|-- DirectedHypergraph
    IHypergraph <|-- IUndirectedHypergraph
    IUndirectedHypergraph <|-- Hypergraph
    IUndirectedHypergraph <|-- MultiplexHypergraph
    IUndirectedHypergraph <|-- TemporalHypergraph

I've included detailed commit messages, as well as comments describing my changes. The key differences in functionality now, though are:

• Instead of using edge_id's to access values in the _edge_metadata structures, I've set them up to index them directly, using the edges' tuples. The previous method seemed needlessly complicated, at least within the class definitions, since the edges were used to look up the edge_ids every time.
• I added lots more type checking to the class constructors and methods, to cut down on ambiguity (especially around the _edge_list dicts, may rename that later)
• edge_metadata is typechecked to ensure only lists of dictionaries are allowed, no sets, dicts, or anything else like before. that way, the IHypergraph constructor can reliably map them to dicts of type Dict[Tuple, Dict].

[FraLotito]

This looks very useful! Thanks a lot for working on it, it is very needed. I'll take some time to review the code (may be slow due to holidays) and reach out for further questions / merge the code:)