.Net: Change Agents.Abstractions to depend on SemanticKernel.Abstractions instead of SemanticKernel.Core

[markwallace-microsoft]

Motivation and Context

Closes #10571

Description

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]

Waiting on feedback from @crickman

[crickman]

Feels like we're still missing the case were an Azure Agent or Assistant was created with a template and the rehydrated from an existing model/definition via retrieval by its identifier.

In that case, would the developer be expected to also provide the full template config?

What would be the behavior when the provided template config doesn't match this existing definition?

[markwallace-microsoft]

Feels like we're still missing the case were an Azure Agent or Assistant was created with a template and the rehydrated from an existing model/definition via retrieval by its identifier.

In that case, would the developer be expected to also provide the full template config?

What would be the behavior when the provided template config doesn't match this existing definition?

This case needs to be handled as part of the declarative agent framework. My initial thought is that it should be possible to override instructions, provide additional tools, etc for an already deployed agent. Overriding instructions will be useful if the template contains values that are related to the current request.