Build a bundled CLI with webpack for performance

This reduces startup time on my machine by approx 40%, likely much more
on machines with non-SSDs or active AV. Will also allow us (shortly) to
dramatically shrink the deployed server size too.

Author: pimterry

.gitignore

@@ -54,3 +54,5 @@ yarn-error.log*
 
 __pycache__
 *.pyc
+
+bundle/