refs #17468, update in source comments and examples to AMD syntax

I'm frustrated seeing end users struggle by looking at API docs for core Dojo methods and finding pre-AMD examples in the API viewer.

While I hate churning this much code in code (even though it's just comments), this has to be fixed. I've started with a handful of files. I would appreciate a review/sanity check, or even better, some help in fixing this problem.

https://bugs.dojotoolkit.org/ticket/17468