Improve and extend our custom collection types

[jix]

We're using quite a few custom collection types, mostly TableSeq, IdVec or collections built on top of them (like IndexedIdVec) or otherwise related to TableSeq or Id types. I want to improve these in the following ways:

• Implement more methods
  • Often there are standard library collection types that offer good guidance on which methods are useful for certain kind of collections
• Offer more specialized wrappers for common use cases, e.g.:
  • TableSeq<T> corresponds (usage wise) to a Vec<HashTable<T>> but many uses of it could be a Vec<HashSet<T>> or Vec<HashMap<K, V>> so adding a SetSeq<T> and MapSeq<K, V> makes sense.
  • Often the subtable index for a TableSeq<T> (or future SetSeq<T> and MapSeq<K, V>) is the id_index() of an Id type, so Id{Table,Set,Map}Seq types would be useful
  • Polarity aware types that are indexed by a Var but allow insertion and querying using a Lit, automatically applying Boolean negation to the stored values as appropriate. This requires some currently missing traits to classify which types support Boolean negation (see also #7)
  • Have custom order preserving set and map types.
    • Essentially what the 3rd party indexmap crate offers, but more memory efficient
      • indexmap always uses a hashtable of 64-bit indices and caches the 64-bit hash value for all entries, that ends up using almost 3x as much memory as needed in most of our use cases
    • IndexedIdSet<u32, T> is essentially what this should be, but that doesn't have a great API for this use case because it also wants to be a map type with u32 keys
    • The index type used should be appropriately sized for the contained type or known size bound, e.g. when adding optional support for 64-bit Var/Lit, it should be IndexedIdSet<u64, T> instead of IndexedIdSet<u32, T>

[jix]

I've started implementing some of this, as I needed it for something else I was working on, but I still need to extract it into a separate branch to turn it into at least a WIP PR.

[jix]

The PR #13 adds SetSeq and IdSetSeq.

[jix]

PR #17 provides the order preserving types mentioned in the issue