Python: Forward provider config to SessionConfig in GitHubCopilotAgent (fixes…

[Serjbory]

Fixes #5190

Motivation and Context

GitHubCopilotAgent does not forward the provider field from default_options (or runtime options) to the Copilot SDK's SessionConfig / ResumeSessionConfig. This makes BYOK (Bring Your Own Key) and Azure Managed Identity authentication impossible through the Agent Framework wrapper, even though the underlying github-copilot-sdk fully supports ProviderConfig on both config types.

Description

Follow the established mcp_servers pattern to add provider passthrough:

• Import ProviderConfig from copilot.types.
• GitHubCopilotOptions TypedDict: Add provider: ProviderConfig field with docstring for discoverability and type safety.
• __init__: Pop provider from the options dict and store it as self._provider (same as mcp_servers, on_permission_request, etc.), so it does not leak into _default_options.
• _create_session: Resolve provider from runtime_options first, falling back to self._provider, and forward it to SessionConfig.
• _resume_session: Forward self._provider to ResumeSessionConfig.
• Tests: Add TestGitHubCopilotAgentProvider class with 7 tests covering:
  • Provider passed to create_session (Azure + bearer_token)
  • Provider passed to resume_session
  • Config excludes provider when not set (both create and resume)
  • Runtime provider takes precedence over default
  • Provider is popped from opts and not leaked into _default_options
  • Provider coexists with model, tools, and mcp_servers

Contribution Checklist

• The code builds clean without any errors or warnings
• The PR follows the Contribution Guidelines
• All unit tests pass, and I have added new tests where possible
• Is this a breaking change? If yes, add "[BREAKING]" prefix to the title of the PR. — No, this is a purely additive change.

[eavanvalkenburg]

@Serjbory please pull in the latest changes and make the updates!

[Serjbory]

@Serjbory please pull in the latest changes and make the updates!

@eavanvalkenburg updates are done. Could you review it, please?

[moonbox3]

Python Test Coverage Report •

File	Stmts	Miss	Cover	Missing
packages/github_copilot/agent_framework_github_copilot
_agent.py	268	12	95%	37–38, 44, 63, 370–371, 646–647, 662, 665, 732, 757
TOTAL	27205	3184	88%

Python Unit Test Overview

Tests	Skipped	Failures	Errors	Time
5446	20 💤	0 ❌	0 🔥	1m 29s ⏱️