adding Retrieval Bot sample

[sakov-ms]

Added the Retrieval Bot sample that will work for Build.

[Copilot]

Pull Request Overview

This PR adds a new Retrieval Bot sample for the Build Conference 2025, including all necessary solution, project, configuration, plugin, and controller files to launch a .NET web service bot that integrates with Microsoft Graph and Semantic Kernel. Key changes include:

• Addition of multiple solution and project files along with configuration files (appsettings.json, .gitignore, and manifest.json)
• Implementation of various plugins (e.g., AdaptiveCard, SendMail, BuildRetrieval) and an agent class that leverages them
• Setup of authentication and bot controllers for handling messages

Reviewed Changes

Copilot reviewed 124 out of 124 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
Microsoft.Agents.M365Copilot.sln	Adds new solution to support the Retrieval Bot sample
.gitignore	Includes standard Visual Studio exclusions for the new project
appsettings.json	Configures authentication, token validation, and AI service parameters for the bot
RetrievalBot.sln & RetrievalBot.csproj	Define the solution and project structure; note duplicate package references
RetrievalBot.cs	Implements the core bot functionality using the Retrieval Agent
Various Plugins & Controllers	Introduce functionality for adaptive cards, email sending, contact retrieval, etc.
AspNetExtentions.cs & manifest.json	Provide authentication setup and app manifest for Teams integration

Comments suppressed due to low confidence (1)

samples/complex/RetrievalBot/dotnet/RetrievalBot/RetrievalBot.cs:30

• [nitpick] The variable name 'weatherAgent' is misleading since the agent handles retrieval tasks; consider renaming it to 'retrievalAgent' for clarity.

RetrievalAgent weatherAgent = new RetrievalAgent(_kernel, this);