- Added common.proto to host NodeMetadata
- go_package names were fixed up so imports are generated with the proper
package names
- fixed up build work (dockerfile) to prevent copying the previously
generated go proto files. This fixes a bug where we could incorrectly
copy the previously generated protobuf instead of a new one generated
at an incorrect location/name/etc.
Signed-off-by: Brad Beam <brad.beam@talos-systems.com>