Continuous releases of the JS library

[asfimport]

To help people test new features and detect bugs early, we should make regular releases of the JS package. This could be nightly or whenever we merge a pull request with a JS tag on it. I think the latter would be better since it would reduce the number of releases significantly.

Releases should be tagged as canary. http://npm.github.io/publishing-pkgs-docs/updating/using-tags.html

Reporter: Dominik Moritz / @domoritz

_{Note: This issue was originally created as ARROW-14508. Please see the migration documentation for further details.}

[domoritz]

This would be nice but doesn't work easily with the apache release model.