Support EXT_shader_texture_lod on Vulkan.
Support EXT_shader_texture_lod on Vulkan.

Bug: angleproject:2899,b/161716126
Change-Id: Ia850cbda948c8f6da9ced0bf46fd7f8371125032
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2288333
Reviewed-by: Tim Van Patten <c7814369a8d3d5671c484acc7b3215f1bf4221be@google.com>
Commit-Queue: Geoff Lang <b6fc25fe0362055230985c05cbfa8adb741ccc0f@chromium.org>

ppy/angle,ppy/angle,ppy/angle,ppy/angle