Golang x/build: add binary size sparklines to build.golang.org

Binary size keeps creeping up. Some visibility might help.

Here's an idea: At the end of every builder run, we have readily available a bunch of compiled binaries on a bunch of different platforms. We could pick a few binaries on a couple of platforms and add some spark charts (or regular charts) to the top of build.golang.org of binary sizes.

I'd like to do the same with compile time, etc, but that information is less readily available.

Related: #19327

cc @dmitshur @bradfitz

Comment From: ALTree

Implemented in the new perf dashboard! Closing here.