Move all to do w/ protobuf -- *.proto files and generated classes -- under hbase-protocol

To better contain our protobuf exposure, keep all to do w/ protobuffing inside the hbase-protocol module.

This task moves rest, examples, and server proto files that do testing and CP endpoints etc., under hbase-protocol. The patch is big but it is all just moving files.

interesting to see the copy-paste being done everywhere of proto generation. For this reason alone, it is better to have all the protos in the one place beside doc on how-to, etc.