Simplify GitHub API request method forwarding

Use the validated request method when building the host-mediated GitHub API RPC payload instead of duplicating the GET literal.

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

Author: jchuerva

nodejs/src/session.ts

@@ -1408,7 +1408,7 @@ export class CopilotSession {
         validateGitHubApiRequest(request);
         const response = await this.rpc.api.github.request({
             scope: "current_repository",
-            method: "GET",
+            method: request.method,
             path: request.path,
             query: request.query,
             paginate: request.paginate,