Support for (CSI) volumes

[waxie]

Would be great to be able to see status of (CSI) volumes in Hashi UI:

• https://www.nomadproject.io/docs/internals/plugins/csi
• https://www.nomadproject.io/docs/job-specification/csi_plugin
• https://www.nomadproject.io/docs/commands/volume
• https://www.nomadproject.io/api-docs/volumes

For example:

• volume status: is volume attached to job/node
• manage volume (create/delete, register/deregister, attach/detach)

[waxie]

NOTE: This also means a Rolling restart through Hashi-UI of jobs containing CSI volumes is broken:

Unexpected response code: 500 (rpc error: 1 error occurred: * Task group xxx validation failed: 1 error occurred: * Task group volume validation for xxxx failed: 2 errors occurred: * CSI volumes must have an attachment mode * CSI volumes must have an access mode )

Even worse if you do Stop/Start: the job gets stopped (and then fails to start with same error)