Ask for password if absent

[andreasabel]

cabal upload asks for the password if not stored in .cabal/config. I'd prefer this behaviour for hackage-cli, too. That is, if password is missing in .netrc then haskage-cli should ask for it on the command line.

Originally posted by @amigalemming in https://github.com/hackage-trustees/hackage-cli/issues/8#issuecomment-1432887534