Add Jenkins integration

[willholley]

#1 adds chart testing using KinD. It should be possible to run these as a CI check in Jenkins, assuming we can get this repository hooked up.

Is there more to it than just adding a Jenkinsfile?

[wohali]

@willholley You'll need to create a new CouchDB Helm Jenkins job in the CouchDB folder over at builds.apache.org. You can copy the current setup for mine if you like, though you may want to add a new set of credentials so GH doesn't throttle because of excessive API endpoint usage.

You'll need to get access to add new jobs there, which I believe requires @janl to approve a request you make through ASF Infra JIRA.

[willholley]

@janl are you able to grant me access to CouchDB build jobs in Jenkins? The infra wiki and recent Jira tickets suggest this may be self-service for PMC chairs by adding me to the hudson-jobadmin group in LDAP using whimsy.

If not, I'll open an infra ticket as @wohali suggested.

[willholley]

replaced by #80