fix(metadata): support metadata download durng `npm install`
fix(metadata): support metadata download durng `npm install`

It turns out the fix for downloading metadata in the Docker images from
https://github.com/pelias/geonames/pull/398 did _not_ work.

We need to allow NPM scripts during `npm install` so that, among other
things, better-sqlite3 can install its Node.js bindings.

In the long run, I wonder if we should rethink the entire metadata
approach. Surely it makes sense to treat it as part of the regular
download process like we do the `inventory.json` file for the WOF
download.

But for the short term I wanted to fix the issue without making any
changes to peoples workflows or any significant code changes.

So this PR adds _just_ enough files to the Docker image before `npm
install` is run so that the metadata download will work. We don't want
to copy _all_ the code files first: that would make repeated docker
builds slower during local development. This should be a decent middle
ground that gets things working again.

pelias/geonames,pelias/geonames