dev/ci: deploy npm pull-through cache

Created by: bobheadxi

Flakes as a result of npm failures have become a quite common source of failures:

sum(count by (build) (count_over_time({app="buildkite",branch="main",state="failed"}
|= "An unexpected error occurred: \"https://registry.npmjs.org/"[1d])))

https://sourcegraph.grafana.net/goto/GEAhSC6nk?orgId=1 (I think this is a correct query)

We should investigate deploying a pull-through cache for npm to mitigate these issues, such as Verdacio:

Verdaccio is a simple, zero-config-required local private NPM registry. No need for an entire database just to get started. Verdaccio comes out of the box with its own tiny database, and the ability to proxy other registries (eg. npmjs.org), also introduces caching the downloaded modules along the way. For those who are looking to extend their storage capabilities, Verdaccio supports various community-made plugins to hook into services such as Amazon's S3, Google Cloud Storage or create your own plugin.