cleosrv: Finish restructuring CLI app to match cleoc

See for example f57cae0638 how it was done for cleoc. The goal is mostly to simplify testing. Symmetry with cleoc makes it easier to maintain and understand.

I started for cleosrv with commit 75e149303f7d .

Compare cleosrv with the restructuring shown in commits f57cae0638 and 75e149303f7d, starting with the current CLI app structure and its tests. Follow the cleoc pattern where applicable; done means cleosrv has the intended symmetry and testing is simpler.

Written by the indexing model from the issue text.