Implement feedback from Iteration I #376

Improvements from our first look at the v6 client with @g-despot

• "Autocomplete" gRPC host when connecting to WCD (prepend grpc-) (Part of Authentication and connection helpers #380)
• Check that all lambda-builder fields are private (they’re visible at the moment)
• Do add overloaded methods for CollectionDefinition.Builder.vectors that correspond to each one of the Vectors.of overloads. Saves unnecessary typing. Postponed to a later stage.
• Implement nearText search
• Add Weaviate Embeddings vectorizer
• Add blob data type to store images (useful for the POC Spring app) (create collection / insert data / query)
• GroupBy with a “reference” property

Wrt this:

• Add overloaded methods for CollectionDefinition.Builder.vectors that correspond to each one of the Vectors.of overloads. Saves unnecessary typing.

Not exactly sure about that, as it does seem to add "many ways to do the same thing". My current approach is to add 1 method to the "builder", e.g. vectors(Vectors v) and always have the user use one of the overloaded Vectors.of() constructors.

Same for references, vector indices, and any other time we use some abstraction over the actual data.

Metting notes: 📔