This commit add zsh completions for the keydb `client`. They have contextual host completion and full argument descriptions.
Vendor-distributed completions for zsh should end up in `/usr/share/zsh/vendor-completions`, but unfortunatly I'm not familiar with the packaging method for *.deb archives, so these completions will need to be moved to the appropriate directory.
Former-commit-id: f77980fce87f22b59677e374e0d5c113775cc08a
