fuchsia: Add vulkan loader service to sandbox policy

Since 57a19db65282 ("[fuchsia] Whitelist required Fuchsia services in
component manifest.") vulkan fails to initialize. Fix it by adding
the vulkan loader service to the policy.

Bug: 861853
Test: content_shell --ozone-platform=scenic --enable-vulkan --disable-gpu

Change-Id: I38c11f32e0a0dd8b914184a16198c023877a0572
Reviewed-on: https://chromium-review.googlesource.com/1228488
Reviewed-by: Sergey Ulanov <sergeyu@chromium.org>
Commit-Queue: Michael Spang <spang@chromium.org>
Cr-Commit-Position: refs/heads/master@{#592126}
2 files changed