Add continuous deployment for NPM package publication

[cxkoda]

This adds continuous deployment of the NPM package for the main branch.

Each time something is pushed to main (including PR merges) and testing + linting is successful, a publication of the NPM package will be triggered.
The published version is determined from the version in the package.json. If it did not change between merges, the deployment will be skipped.

NPM_TOKEN needs to be added as an action secret to the repo settings.

Further, I recommend that we add the following branch settings for main:

• Protect (no direct pushes)
• Require a pull request before merging
  • opt. Require approvals
• Require status checks to pass before merging
• Require branches to be up to date before merging

[cxkoda]

I moved the definition of the commands that are executed by the CI over to NPM scripts. This allows us a better handling of what happens and easier execution locally. Further I changed to gofmt instead of goimport, which was a nightmare to get to work.