.Net: Adding Qdrant generic data model mapper.

[westey-m]

Motivation and Context

To allow use of the vector store abstractions without needing to define your own data type, we are adding a generic data type and mappers that can work with it.

Description

• Separate field mapping functions into a separate class for Qdrant, so that it can be reused across mappers.
• Adding a mapper for the generic data type for Qdrant
• Adding some small improvements to Azure AI Search's mapper.

Contribution Checklist

• The code builds clean without any errors or warnings
• The PR follows the SK Contribution Guidelines and the pre-submission formatting script raises no violations
• All unit tests pass, and I have added new tests where possible
• I didn't break anyone 😄