[JAMES-3226] Starting a new website build

* Removed old content since it was generated, and not source
* Added .asf.yaml file to output
* [JAMES-3226] #comment Initialized gradle + antora playbook
* [JAMES-3226] #comment Using gradle plugin to download nodejs and antora
* [JAMES-3226] #comment Added Jenkinsfile
* [JAMES-3226] Publish the staging website automatically
17 files changed