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

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

dev-infra/pr/merge/pull-request.ts

@@ -17,6 +17,8 @@ import {PullRequestMergeTask} from './task';
 
 /** Interface that describes a pull request. */
 export interface PullRequest {
+  /** URL to the pull request. */
+  url: string;
   /** Number of the pull request. */
   prNumber: number;
   /** Title of the pull request. */
@@ -33,6 +35,8 @@ export interface PullRequest {
   requiredBaseSha?: string;
   /** Whether the pull request commit message fixup. */
   needsCommitMessageFixup: boolean;
+  /** Whether the pull request has a caretaker note. */
+  hasCaretakerNote: boolean;
 }
 
 /**
@@ -77,13 +81,17 @@ export async function loadAndValidatePullRequest(
       config.requiredBaseCommits && config.requiredBaseCommits[githubTargetBranch];
   const needsCommitMessageFixup = !!config.commitMessageFixupLabel &&
       labels.some(name => matchesPattern(name, config.commitMessageFixupLabel));
+  const hasCaretakerNote = !!config.caretakerNoteLabel &&
+      labels.some(name => matchesPattern(name, config.caretakerNoteLabel!));
 
   return {
+    url: prData.html_url,
     prNumber,
     labels,
     requiredBaseSha,
     githubTargetBranch,
     needsCommitMessageFixup,
+    hasCaretakerNote,
     title: prData.title,
     targetBranches: getBranchesFromTargetLabel(targetLabel, githubTargetBranch),
     commitCount: prData.commits,