Use Qdrant.Client for QdrantMemory internals

[russcam]

This commit updates QdrantMemory to use the official Qdrant client for QdrantMemory internals.

I wanted to open a PR at this stage to gauge interest in this change. Further work needed to remove the current client implementation and to test adapters between Kernel memory and Qdrant client is needed.

Motivation and Context (Why the change? What's the scenario?)

• The official client uses gRPC rather than JSON over REST, with gRPC typically offering a significant overall performance improvement.
• Official client is maintained by Qdrant, reducing code needing to be maintained in this repository to interface with Qdrant

High level description (Approach, Design)

• Replace the internal qdrant client implementation with the official Qdrant client, mapping the current client's implementation to methods of the official client.
• Adapt kernel memory types like MemoryRecord to Qdrant types. There may be opportunities to make this smoother.