Support for OAuth Authentication  for GitHub and Bitbucket

• Evaluate using https://www.npmjs.com/package/oauth, other Java-based, or implementing our own [1] (Quarkus-based)
• Must be generic, as we can have multiple OAuth apps that need to work (e.g. GitHub, Bitbucket, GitLab etc)

• Configure GitHub and Bitbucket apps and its secrets/clientKeys on our CI / Release jobs
• We’re going to need new build-time env variables (or env.json) entries to provide the URLs of such OAuth applications.
• Document how to do the same for on-prem use, as customers will need to create their own OAuth apps to use for authentication.
• Make KIE Sandbox UI consume those OAuth services, and remove the manual Token authentication mechanism
• Tokens will be persisted ONLY on the browser Cookies