chore(hashing): use only @node-rs/xxhash with bigint(s)

[folkvir]

Changes

• Remove xxhashjs
• Use @node-rs/xxhash everywhere
  • Since xxh64 returns bigint(s) we now use bigints everywhere.

The critical part are:

• doubleHashing
  • depending on your review, we may want to return only numbers because the produced nhash should be on [0, tableSize). And will probably never be higher than Number.MAX_SAFE_INTEGER which is 9007199254740991 in node 22 😆 . Aka we will call bigIntToNumber() directly in the function.
• cuckoo indexes creation