Restored DurableHNSWCorpus + adjusted to new SNLPCorpus protocol

...P/1. Data Collection/DurableHNSWCorpus + Dictionary.swift

...tNLP/1. Data Collection/DurableHNSWCorpus + File IO.swift

...NLP/1. Data Collection/DurableHNSWCorpus + Sequence.swift

Sources/SwiftNLP/1. Data Collection/DurableHNSWCorpus.swift

...ces/SwiftNLP/1. Data Collection/EphemeralHNSWCorpus.swift

Sources/SwiftNLP/2. Encoding/CoreMLEncoder.swift

Sources/SwiftNLP/2. Encoding/NatualLanguageEncoder.swift

Sources/SwiftNLP/2. Encoding/OpenAIEncoder.swift

...ests/1. Data Collection/HNSW/DurableHNSWCorpusTests.swift

...ts/1. Data Collection/HNSW/EphemeralHNSWCorpusTests.swift