Like copyTextureCHROMIUM in Chromium, CopyImageBitmapToTexture can use
internal pipeline to do the GPU uploading. But Dawn doesn't support
internal pipeline now.
This patch adds the first internal pipeline for Dawn and add the API
CopyTextureForBrowser to use internal pipeline to do gpu uploading.
The patch integrates very simple wgsl vertex/fragment shaders to do
simple direct blit to verify the whole system works.
BUG=dawn:465
Change-Id: I8b566af38a10eea00f7426c39e752958ef057abd
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/30960
Commit-Queue: Shaobo Yan <shaobo.yan@intel.com>
Reviewed-by: Austin Eng <enga@chromium.org>
db8766bb23