[VC] no checkmark for selected template in breadcrumb

The checkmark is not shown when a template is selected from breadcrumb
dropdown list as templateId used in aria checked in SeaPenTemplateId
type. It needs to convert to string for comparison.

Bug: b/332899230
Test: Verify UI - http://screen/8qu7E2SyicAv2f6
Test: browser_tests --gtest_filter="*VcBackground*"
Change-Id: Ib3be28d19a66efc49b7c29b198bc1fad965ff4d1
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5425576


Commit-Queue: Thuong Phan <thuongphan@chromium.org>
Reviewed-by: Jason Thai <jasontt@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1282741}