Group D3D11 DXGI format info under a struct This patch refactors how DXGI format info is stored. The goal is to make it easier to make changes that affect both swizzle formats and regular texture formats, and make it easier to pass the format sets around. BUG=angleproject:1244 TEST=angle_end2end_tests Change-Id: I1cc220bccbbdde9200a41829fdc37c8ec123c6a1 Reviewed-on: https://chromium-review.googlesource.com/329072 Reviewed-by: Corentin Wallez <cwallez@chromium.org> Commit-Queue: Olli Etuaho <oetuaho@nvidia.com>