Publish packages

[kulmann]

In order to make oC Web app development more convenient (see #7930 for context) we want to publish the packages web-client (API abstraction layer) and web-pkg (helpers for app developers, including opinionated components and quite some composables) to npmjs.com

Some thoughts that @dschmidt and I discussed today as for how we want to start publishing packages from our monorepo and gain some experience with it:

• packages that are to be published to npmjs.com are design-system, web-client and web-pkg
• ownCloud Web (the full bundle) doesn't get published to npmjs.com but released on github, as we already do it today
• all those 4 deliverables receive their own version number and their own git tags, to be precise:
  • oC Web with version v7.0.0-rc.x. The tag won't have a prefix as it is the main release from the repo
  • design-system with tag design-system-v15.0.0 or with suffix -alpha.x etc
  • web-client with tag web-client-v0.1.0 or with suffix -alpha.x etc
  • web-pkg with tag web-pkg-v0.1.0 or with suffix -alpha.x etc
• at the moment we publish to npmjs.com as @ownclouders, i.e. packages on npmjs.com will be @ownclouders/web-client etc.
• all packages receive their own changelog folder and changelog generation with calens
• all packages get their version number updated in their package.json file respectively - without any automagic version calculation. We continue to specify versions manually. Our changelog conventions make it super easy to find out the next version number.