Remove SemanticKernel and KernelMemory

[martindevans]

Removes Semantic Kernel and Kernel Memory integrations.

Kernel memory has been marked as an archived project:

This is an archived research project. The code serves as a learning resource, not production software. Use it with caution, and at your own risk. No support is provided.

Semantic Kerne has been replaced by Microsoft Agent Framework:

Semantic Kernel is now Microsoft Agent Framework! Microsoft Agent Framework (MAF) is the enterprise‑ready successor to Semantic Kernel.

[martindevans]

Resolve #693