When sending a key to a key server there's no feedback on whether the operating
succeeded, neither by default nor after adding --verbose or --debug.

I understand that no feedback usually means success on the command line, but I
suggest returing "Key successfully sent to the key server" with the --verbose
option.

This made me wonder whether the operation succeeded while submitting a key to a
private key server for a keysigning party such as described in
https://people.debian.org/~lunar/blog/posts/ksp_keyserver/.

After seeing #1832 I realized that I have no other option that asking the admin
of the keyserver to know if it really succeeded.