build: use npm pack tarball for local examples and testing instead of .local

[broofa]

@ctavan, I don't expect this to be controversial but it'd be nice to get your sign off here since the ".local" directory setup was initially your idea.

Briefly, this does the following:

1. Have the build script create an npm pack tarball (in .build/uuid.tgz) that can be installed locally
2. Have all examples use that instead of the ".local" dir
3. Remove the .local dir

Note

npm install in the examples/* dirs was failing on GH test runners because npm pack's output is platform specific. This tends to cause npm to complain when it compares the checksum it sees on one platform (GH runner) to the integrity checksum it caches in package-lock.json on another platform (like our laptops). The workaround was to add the --no-package-lock when installing in examples/* dirs. This isn't a big deal since the only thing being installed is the uuid tarball. And it has the nice side-effect of removing the need for package-lock.json files in those dirs.

[broofa]

Merging, as I need this for #860