.NET: Add Hosted-MemoryAgent sample with isolation key plumbing (#5692)#5702

rogerbarreto wants to merge 2 commits intomicrosoft:mainmicrosoft/agent-framework:mainfrom

rogerbarreto:issues/5692-net-hosted-agents-foundry-memory-samplerogerbarreto/agent-framework-public:issues/5692-net-hosted-agents-foundry-memory-sampleCopy head branch name to clipboard