Add support for bearer token - semantic kernel sample

[Josina20]

No description provided.

[Copilot]

Pull request overview

This PR adds support for bearer token authentication as an alternative to the existing authentication handler in the Semantic Kernel sample agent. The change allows the agent to bypass the standard "MyAuth" sign-in handler when a bearer token is provided via environment variable, enabling scenarios where token-based authentication is preferred over interactive authentication flows.

Key changes:

• Adds BEARER_TOKEN environment variable configuration for development
• Conditionally disables auto-signin handlers when bearer token is present
• Passes bearer token to tool service for authentication when USE_AGENTIC_AUTH is false

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 7 comments.

File	Description
dotnet/semantic-kernel/sample-agent/Properties/launchSettings.json	Adds BEARER_TOKEN environment variable configuration for development launch settings
dotnet/semantic-kernel/sample-agent/Agents/MyAgent.cs	Implements conditional logic to skip auto-signin handlers when bearer token is configured, and adds new InstallationUpdate route registration
dotnet/semantic-kernel/sample-agent/Agents/Agent365Agent.cs	Adds bearer token retrieval and conditional passing to tool service based on authentication mode