Chore: Report betterer stats in ci-frontend-metrics (#47210)

* Chore: Report betterer stats to graphite

* PR feedback

* use camelCase from lodash instead

scripts/cli/reportBettererStats.ts

@@ -0,0 +1,21 @@
+import { betterer } from '@betterer/betterer';
+import { camelCase } from 'lodash';
+
+function logStat(name: string, value: number) {
+  // Note that this output format must match the parsing in ci-frontend-metrics.sh
+  // which expects the two values to be separated by a space
+  console.log(`${name} ${value}`);
+}
+
+async function main() {
+  const results = await betterer.results();
+
+  for (const testResults of results.resultSummaries) {
+    const name = camelCase(testResults.name);
+    const count = Object.values(testResults.details).flatMap((v) => v).length;
+
+    logStat(name, count);
+  }
+}
+
+main().catch(console.error);