Some bits of information, like the copy functions and mipmap gen
functions, can be shared across back-ends in the angle::Format
class.

Also name the info struct angle::Format, and use an enum class
angle::Format::ID to identify the particular format.

This patch introduces a new table generator for angle formats
and updates the D3D11 generator accordingly.

BUG=angleproject:1455

Change-Id: I13b8b98822b1186c6a9e436dc232c18fef50980c
Reviewed-on: https://chromium-review.googlesource.com/365824Reviewed-by: Zhenyao Mo <zmo@chromium.org>
Reviewed-by: Geoff Lang <geofflang@chromium.org>
Commit-Queue: Jamie Madill <jmadill@chromium.org>