refactor(dev-infra): use a singleton for GitClient (#41515)

Creates a singleton class for GitClient rather than relying on creating an instance to
require being passed around throughout its usages.

PR Close #41515

dev-infra/utils/git/github-yargs.ts

@@ -7,8 +7,11 @@
  */
 
 import {Argv} from 'yargs';
+
 import {error, red, yellow} from '../console';
+
 import {GITHUB_TOKEN_GENERATE_URL} from './github-urls';
+import {GitClient} from './index';
 
 export type ArgvWithGithubToken = Argv<{githubToken: string}>;
 
@@ -29,6 +32,7 @@ export function addGithubTokenOption(yargs: Argv): ArgvWithGithubToken {
             error(yellow(`You can generate a token here: ${GITHUB_TOKEN_GENERATE_URL}`));
             process.exit(1);
           }
+          GitClient.authenticateWithToken(githubToken);
           return githubToken;
         },
       })