Rather than importing the script with a <script> tag, use angular's
build system to import the script. This makes our HTML consistent
internally and externally, and is probably the way to go if we want to
use the library in unit tests.
Build a self contained channelz.js from a channelz.proto.
Running buildscripts/channelz_codgen.sh will produce a
web/channelzui/src/assets/channelz.js that reflects the SHA
specified in the scripts.
The script fetches grpc/grpc-web to get the prereq docker image, does
some additional setup, and then runs the code gen script.
zpencer