CCA: Fix unclickable link in barcode chip

This CL fixes a regression after we adapt responsive layout. We have
|pointer-events: none| on preview-box so we have to re-enable pointer
events on barcode chip container.

This does not caught by the Tast test because we "click()" the link
directly which ignores the pointer-events settings.

Bug: b/172879638
Test: Manually
Change-Id: I0a7a1a3a755ff1d37a7e7f3f25229a0c97ced16a
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2619445
Auto-Submit: Shik Chen <shik@chromium.org>
Commit-Queue: Inker Kuo <inker@chromium.org>
Reviewed-by: Inker Kuo <inker@chromium.org>
Cr-Commit-Position: refs/heads/master@{#841955}

chromeos/components/camera_app_ui/resources/css/main.css

@@ -1609,6 +1609,7 @@ body.photo.scan-barcode .barcode-scan-box {
   left: 50%;
   max-width: min(80%, var(--chip-max-width));
   opacity: 1;
+  pointer-events: auto;
   position: absolute;
   /* Avoid collision with scan-box and preview-box */
   top: max(8px, min(10%, 33.33% - var(--text-line-height) -