.Net: Memory Plugin extraction - Part 2

[dmytrostruk]

Motivation and Context

This PR contains changes to mark Memory-related functionality in Kernel as Obsolete and create alternative methods in Plugins.Memory and Connectors projects.

Note: Obsolete methods and properties will be removed in future releases.

ADR: 0011-memory-as-plugin.md

Main change: helper methods for Memory were moved from KernelBuilder to MemoryBuilder. Previously, it was possible to configure only one Memory instance per Kernel instance. Now, Memory functionality is decoupled from Kernel and should be configured separately.

Previous Memory usage:

var kernel = Kernel.Builder
    .WithOpenAITextEmbeddingGenerationService("text-embedding-ada-002", TestConfiguration.OpenAI.ApiKey)
    .WithMemoryStorage(new AzureCognitiveSearchMemoryStore(TestConfiguration.ACS.Endpoint, TestConfiguration.ACS.ApiKey))
    .Build();

kernel.Memory.SaveInformationAsync(...);

New Memory usage:

var memory = new MemoryBuilder()
    .WithOpenAITextEmbeddingGenerationService("text-embedding-ada-002", TestConfiguration.OpenAI.ApiKey)
    .WithMemoryStore(new AzureCognitiveSearchMemoryStore(TestConfiguration.ACS.Endpoint, TestConfiguration.ACS.ApiKey))
    .Build();

memory.SaveInformationAsync(...);

Description

1. Added MemoryBuilder as equivalent to KernelBuilder to initialize the logic related to Memory.
2. Added unit tests for MemoryBuilder.
3. Added extension methods for MemoryBuilder related to Memory and AI Connectors.
4. Marked Memory-related methods and properties in Kernel/KernelBuilder as obsolete.

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 😄

[markwallace-microsoft]

I've added the breaking change tag to this PR as we expect developers to make a code change and this will get the PR listed in the release notes accordingly.

We want to make it easy for developers to understand and adopt the new pattern. Can you:

1. Update the PR description to that includes some instructions on how developers should change their code. It should read like a step by step migration guide.
2. Add sufficient information to the obsolete message so developers know what they need to change. We don't have a good pattern here but maybe a link to a sample, we may even want dedicated samples that show how to change the code i.e. with before and after sample code.