new deploy API following Open API format (#2564)
new deploy API following Open API format (#2564)

* new deploy API following Open API format

* start

* split deployment APIs based on 2 types of objects: config and deployment

* remove host

* modify definitions following comments; add description for experimental APIs

* add delete methods; unify response code

* change following comments

* resolve review feedback; move email to query

kubeflow/kubeflow,kubeflow/kubeflow,kubeflow/kubeflow,kubeflow/kubeflow,kubeflow/kubeflow,kubeflow/kubeflow