.Net: [MEVD] Implemented Delegating classes for vector store abstractions

[dmytrostruk]

Motivation and Context

Related: #10596

This PR contains Delegating classes for vector store abstractions that allows to implement decorators in easier way without a need for implementation of every method when inheriting the interface directly.

The implementation of Delegating class simply calls the methods of inner service.

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 😄

[dmytrostruk]

This will be added later.