drain
Includes: * changes `nomad alloc status` and `nomad node status` * changes to `volume` block in jobspec * new `csi_plugin` block in jobspec * new `nomad volume register/deregister/status` commands * new `nomad plugin status` command
This reverts commit 4311f5e95657a2eb7b231daf326af252e6c75ae7, reversing changes made to 5d5469e6facfc4ab59235d5532664bb95a597728.