feat(cli): allow CLI to report version information
$ jsonnet-tool version
Version: v1.3.0-next
Commit: 6f23752939e96e0a12d35a612a6cf41b359049e0
Date: 2021-08-31T09:02:19Z
Edited by Andrew Newdigate
$ jsonnet-tool version
Version: v1.3.0-next
Commit: 6f23752939e96e0a12d35a612a6cf41b359049e0
Date: 2021-08-31T09:02:19Z