Implement CopyTexture functions for uint texture formats. BUG=angleproject:1932 Change-Id: I6474237cbb82b59a0bd40c1b9b9e2455952d3755 Reviewed-on: https://chromium-review.googlesource.com/600510 Commit-Queue: Geoff Lang <geofflang@chromium.org> Reviewed-by: Corentin Wallez <cwallez@chromium.org>