This makes a few tweaks to get the integration tests passing:
* Add `runtime: nodejs` to the minimal example's `Lumi.yaml` file.
* Remove usage of `@lumi/lumirt { printf }` and just use `console.log`.
* Remove calls to `lumijs` in the integration test framework and
the minimal example's package.json. Instead, we just run
`yarn run build`, which itself internally just invokes `tsc`.
* Add package validation logic and eliminate the pkg/compiler/metadata
library, in favor of the simpler code in pkg/engine.
* Simplify the Node.js langhost plugin CLI, and simply take an
argument rather than requiring required and optional --flags.
* Use a default path of "." if the program path isn't provided. This
is a legal scenario if you've passed a pwd and just want to load
the package's default module ("./index.js" or whatever main says).
* Add an executable script, lumi-langhost-nodejs, that fires up the
`bin/cmd/langhost/index.js` file to serve the Node.js language plugin.
This change keeps the lumi prefix on our CLI tools.
As @lukehoban pointed out in person, as soon as we do pulumi/coconut#98,
most people (other than compiler authors themselves) won't actually be
typing the commands. And, furthermore, the commands aren't all that bad.
Eventually I assume we'll want something like `lumi-js`, or
`lumi-js-compiler`, so that binaries are discovered dynamically in a way
that is extensible for future languages. We can tackle this during #98.
This restructures the examples directory a bit, into three buckets:
* basic/: simplistic examples, like hello world and whatnot.
* conversions/: actual conversions from existing samples (with the source cited).
* scenarios/: more complex examples that demonstrate various features of the system.
