feat(dev-infra): support for caretaker note label in merge script (#37595) (#37778)

Adds support for a caretaker note label to the merge script.
Whenever a configured label is applied, the merge script will
not merge automatically, but instead prompt first in order
to ensure that the caretaker paid attention to the manual
caretaker note on the PR. This helps if a PR needs special
attention.

PR Close #37595

PR Close #37778

dev-infra/pr/merge/task.ts

@@ -6,10 +6,12 @@
  * found in the LICENSE file at https://angular.io/license
  */
 
+import {promptConfirm} from '../../utils/console';
 import {GitClient, GitCommandError} from '../../utils/git';
 
 import {MergeConfigWithRemote} from './config';
 import {PullRequestFailure} from './failures';
+import {getCaretakerNotePromptMessage} from './messages';
 import {isPullRequest, loadAndValidatePullRequest,} from './pull-request';
 import {GithubApiMergeStrategy} from './strategies/api-merge';
 import {AutosquashMergeStrategy} from './strategies/autosquash-merge';
@@ -23,6 +25,7 @@ export const enum MergeStatus {
   DIRTY_WORKING_DIR,
   SUCCESS,
   FAILED,
+  USER_ABORTED,
   GITHUB_ERROR,
 }
 
@@ -72,6 +75,14 @@ export class PullRequestMergeTask {
       return {status: MergeStatus.FAILED, failure: pullRequest};
     }
 
+    // If the pull request has a caretaker note applied, raise awareness by prompting
+    // the caretaker. The caretaker can then decide to proceed or abort the merge.
+    if (pullRequest.hasCaretakerNote &&
+        !await promptConfirm(
+            getCaretakerNotePromptMessage(pullRequest) + `\nDo you want to proceed merging?`)) {
+      return {status: MergeStatus.USER_ABORTED};
+    }
+
     const strategy = this.config.githubApiMerge ?
         new GithubApiMergeStrategy(this.git, this.config.githubApiMerge) :
         new AutosquashMergeStrategy(this.git);