WIP: intel: Attempt to make MSAA dynamic

This patch series attempts to make MSAA dynamic and no longer rely on shader re-compiles. I've got it mostly passing Jenkins except for coarse which is causing me annoying difficulties (see the last couple patches). Nothing is actually calling for this yet so I'm going to leave it WIP for a while but posting it at least makes it easier for others to review. Also the first 15-20 patches are probably useful anyway so maybe we'll land some of those once they've been reviewed.