Remove all use of package:build

[srawlins]

This is a smaller change than you'd imagine! It's kind of a high number of changed files, but some are small. The bulk of the edits are in tests, and are mechanical.

• Move the mustachio (runtime and aot) compilers to a simpler script.
• Remove generation of the resources file (rarely changes, but I added a TODO).
• Remove dependencies on package:build*
• All existing test cases base (when refactored to use new infra).