test_runner: print failed coverage reports with dot reporter

When coverage threshold is not met, the dot reporter now outputs
the error message so users can understand why tests failed.

Refs: #60884

Author: KJyang-0114

lib/internal/test_runner/reporter/dot.js

@@ -18,6 +18,10 @@ module.exports = async function* dot(source) {
       yield `${colors.red}X${colors.reset}`;
       ArrayPrototypePush(failedTests, data);
     }
+    if (type === 'test:diagnostic') {
+      const levelColor = data.level === 'error' ? colors.red : data.level === 'warning' ? colors.yellow : colors.white;
+      yield `\n${levelColor}${data.message}${colors.reset}\n`;
+    }
     if ((type === 'test:fail' || type === 'test:pass') && ++count === columns) {
       yield '\n';