Assign custom agent to issue via assign_copilot_to_issue

Describe the feature or problem you’d like to solve

I want to assign a Copilot coding agent with a custom agent to an issue via assign_copilot_to_issue

Proposed solution

Add a parameter to the tool that enables passing in the name of the custom agent to assign to the issue.

Example prompts or workflows (for tools/toolsets only)

"Assign the Contoso Implementation Planner agent to Issue #32"