The create/register volume RPCs support a policy override flag for
soft-mandatory Sentinel policies, but the CLI and Go API were missing support
for it.
Also add support for Sentinel warnings to the Go API and CLI.
Ref: https://github.com/hashicorp/nomad/pull/24479
Adds dynamic host volumes to argument autocomplete for the `volume status` and
`volume delete` commands. Adds flag autocompletion for those commands plus
`volume create`.
Ref: https://github.com/hashicorp/nomad/pull/24479
Add new commands for creating, deleting, and listing external storage
volumes. Includes HCL decoding update for volume spec so that we can humanize
capacity bytes input values.