A strictly cosmetic change to move code into alphabetical order.
In working with SecondaryCommandBuffer commands in separate CLs,
it can be difficult/annoying to track which commands are already
in place as some of them are out-of-order. This change puts the
command enums, functions, and processing in alphabetical order
to simplify searching and adding new commands.

Bug: b/154030403
Change-Id: I6dba4cf48d6f27c056585ac633c694e083b1a263
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2158816Reviewed-by: Jamie Madill <jmadill@chromium.org>
Commit-Queue: Tobin Ehlis <tobine@google.com>