Add labels, annotations, volumes mounts, domain templates, ingress class, etc.

Related: Use devfile gem in spike branch (gitlab-org/gitlab#392492 - closed)

Done:

• Add labels and annotations to k8s resource generated
• Add volume and volume mounts for ephemeral volumes
• Add domain template for the ingress host
• Add ingress class for the ingress resource created
• Move built binary to bin instead of lib
• Fix rubocop warnings
• Update CI pipeline to only perform tests
• Add documentation

TODO: This will be done in a followup MR.

• Add YAML options for providing deployment, service, ingress options. This will simplify the UX
• Look into provisioning PVC resources based on devfile volumes