Deprecate use of blockstorage package

Currently for snapshot operations kanister uses blockstorage package, which has several providers abstracting away specific APIs.
Functions like CreateVolumeFromSnapshot use those providers.

Since introduction of CSI volume snapshots this functionality can be done via CSI apis instead of blockstorage providers. The functions currently using blockstorage package can be changed to use CSI and blockstorage package can be deprecated.