Add API method for download scanned repo result

This will download the result for a particular repo by making a call
to the download URL via octokit.

extensions/ql-vscode/src/remote-queries/gh-api/gh-api-client.ts

@@ -74,6 +74,19 @@ export async function getVariantAnalysisRepo(
   return response.data;
 }
 
+export async function getVariantAnalysisRepoResult(
+  credentials: Credentials,
+  downloadUrl: string,
+): Promise<unknown> {
+  const octokit = await credentials.getOctokit();
+
+  const response: OctokitResponse<VariantAnalysisRepoTask> = await octokit.request(
+    `GET ${downloadUrl}`
+  );
+
+  return response.data;
+}
+
 export async function getRepositoryFromNwo(
   credentials: Credentials,
   owner: string,