This commit is the initial implementation of claiming volumes from the
server and passes through any publishContext information as appropriate.
There's nothing too fancy here.
The CSI Spec requires us to attach and stage volumes based on different
types of usage information when it may effect how they are bound. Here
we pass through some basic usage options in the CSI Hook (specifically
the volume aliases ReadOnly field), and the attachment/access mode from
the volume. We pass the attachment/access mode seperately from the
volume as it simplifies some handling and doesn't necessarily force
every attachment to use the same mode should more be supported (I.e if
we let each `volume "foo" {}` specify an override in the future).
This changeset is some pre-requisite boilerplate that is required for
introducing CSI volume management for client nodes.
It extracts out fingerprinting logic from the csi instance manager.
This change is to facilitate reusing the csimanager to also manage the
node-local CSI functionality, as it is the easiest place for us to
guaruntee health checking and to provide additional visibility into the
running operations through the fingerprinter mechanism and goroutine.
It also introduces the VolumeMounter interface that will be used to
manage staging/publishing unstaging/unpublishing of volumes on the host.
