Add "session" command to storage-admin CLI tool for Waltz

[whynick1]

Create a storage-admin CLI command that has the following functionality:

./storage session --partition=[partition_id] --get --set=[session_id]

• Add ability to get session ID for a partition on a storage node
• Add ability to set session ID for a partition on a storage node

See https://confluence.corp.wepay-inc.com/display/DI/Waltz+partition+management+design for context.

[whynick1]

Yes, this feature is not needed to do partition migration. That said, I wanted to include and implement it, as I think it's something that will be generally useful for SREs in cases where the cluster is messed up, or we're running tests. I do agree that it's not high priority.

from @criccomini