Create binary with netsender revid client functionality only

[Saxon Milton]

Currently revid-cli provides both command line and cloud control, but in practice only one of these control methods are used. It therefore doesn’t seem worth the convolution to have a binary that does both of these things. It is therefore proposed that we create a new binary called revid-client, that only provides netsender client functionality and removes anything to do with command line flags and their parsing.