Also reorder fields to reduce space wasted on alignment padding, and
shuffle writing them to the vertex cache in the same order for
consistency.

Bug: b/27351835
Change-Id: I06ca0c836aabd9d095893762d973c098f694ee30
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/32788
Presubmit-Ready: Nicolas Capens <nicolascapens@google.com>
Tested-by: Nicolas Capens <nicolascapens@google.com>
Reviewed-by: Alexis Hétu <sugoi@google.com>
Kokoro-Presubmit: kokoro <noreply+kokoro@google.com>