Added title to test name in snav-testharness.js

Testname is added to snav-testharness.js like testharness.js.
This change will show descriptive test name in the result page.

For example, snav-1st-stop.html
Previously showed on the result page like
[FAIL] Focus movements:\n[["Down","1"]]\n
  eventSender is not defined
Now it will show
[FAIL] [snav-1st-stop] Focus movements:\n[["Down","1"]]\n
  eventSender is not defined

Bug: 40653649
Change-Id: Ic9b6ae4d37d0292b9275eedd23d0549c18c7d3f1
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5612970


Reviewed-by: JunHo Seo <junho0924.seo@lge.com>
Reviewed-by: Fredrik Söderquist <fs@opera.com>
Commit-Queue: Wanchang Ryu <wanchang.ryu@lge.com>
Cr-Commit-Position: refs/heads/main@{#1312654}