message: refactor(build-cli): Automate the main/next integration check
  The SHAs of main and next are compared automatically to verify they're
  in sync. This check is done during a major release to ensure main and
  next are converged before making certain changes.
diff: @@ -287,22 +287,17 @@ export const checkMainNextIntegrated: StateHandlerFunction = async (
  ): Promise<boolean> => {
  if (testMode) return true;
  - const { bumpType, shouldCheckMainNextIntegrated } = data;
  + const { bumpType, context, shouldCheckMainNextIntegrated } = data;
  + assert(context !== undefined, "Context is undefined.");
  - // TODO: Implement this
  if (bumpType === "major") {
  if (shouldCheckMainNextIntegrated === true) {
  - log.warning(`Automated main/next integration check not yet implemented.`);
  - log.warning(`Make sure next has been integrated into main before continuing.`);
  -
  - const confirmIntegratedQuestion: inquirer.ConfirmQuestion = {
  - type: "confirm",
  - name: "integrated",
  - message: `Has next has been integrated into main?`,
  - };
  + const [main, next] = await Promise.all([
  + context.gitRepo.getShaForBranch("main"),
  + context.gitRepo.getShaForBranch("next"),
  + ]);
  - const answers = await inquirer.prompt(confirmIntegratedQuestion);
  - if (answers.integrated !== true) {
  + if (main !== next) {
  BaseStateHandler.signalFailure(machine, state);
  }
  } else {
  