Automate NPM package version bump and publish

[elizabethengelman]

Our current setup to bump the version, and publish the npm loam-cli package involves the following manual steps. Let's automate them both!

• We need to bump the loam-cli npm package version in npm/package.json manually to the same version number of the published loam-cli rust crate.
• We also have a GH action that builds and publishes the npm package to npmjs.com, but this needs to be manually kicked off after the previous step is done. Maybe we should automate this too.