refactor(dev-infra): use shared github repo interface (#38656)

Instead of maintaining multiple interface for grouping
owner name and repo name, we expose a shared interface
describing a Github repository.

One unfortunate downside is that the GraphQL Github
and Rest API diverge slightly with the key for the
repository name. i.e. rest uses `repo` for the name
of a repository, while GraphQL uses `name` for the name.

If that would be consistent, we could use the rest operator
to pass a repository to the Octokit REST or GraphQL API. This
does not work, so we have a small manual overhead as seen
in the `branches.ts` file.

PR Close #38656

dev-infra/utils/git/github.ts

@@ -11,6 +11,14 @@ import * as Octokit from '@octokit/rest';
 import {RequestParameters} from '@octokit/types';
 import {query, types} from 'typed-graphqlify';
 
+/** Interface describing a Github repository. */
+export interface GithubRepo {
+  /** Owner login of the repository. */
+  owner: string;
+  /** Name of the repository. */
+  name: string;
+}
+
 /** Error for failed Github API requests. */
 export class GithubApiRequestError extends Error {
   constructor(public status: number, message: string) {