Initial exploration and planning for clickable issue links in @githubpr chat output

Co-authored-by: alexr00 <38270282+alexr00@users.noreply.github.com>

Author: Copilot

src/@types/vscode.proposed.chatSessionsProvider.d.ts

@@ -210,4 +210,4 @@ declare module 'vscode' {
 		 */
 		export function showChatSession(chatSessionType: string, sessionId: string, options: ChatSessionShowOptions): Thenable<void>;
 	}
-}
+}