Add a pluralize utility function.

source/utilities/exports.ts

@@ -6,4 +6,5 @@ export * from "./groups.js";
 export * from "./logging.js";
 export * from "./query-selectors.js";
 export * from "./report-a-bug.js";
+export * from "./text.js";
 export * from "./validators.js";

source/utilities/text.ts

@@ -0,0 +1,18 @@
+/**
+ * Pluralize a word based on a count.
+ * @param count The number of things.
+ * @param singular The word in its singular form.
+ * @param plural Optionally the word in its plural form. If left undefined the
+ * returned string will be the singular form plus the letter "s".
+ */
+export function pluralize(
+  count: number,
+  singular: string,
+  plural?: string,
+): string {
+  if (count === 1) {
+    return singular;
+  }
+
+  return plural ?? singular + "s";
+}