Nicer password prompt

[squell]

trafficstars

Original sudo has a custom password prompt. It is user friendly to have that. Now most of what we print there is provided by PAM (e.g. Password:, or Yubikey PIN:).

What I propose is a universal prefix-style message, e.g.:

$ sudo whoami
[Sudo:  authenticate as <user> on <host>] Password:

or

$ sudo ls
[Sudo] Smartcard authentication starts
[Sudo] Yubikey found.
[Sudo] Welcome YubiKey PIV Attestation 9a!
[Sudo:  authenticate as <user> on <host>] Yubikey PIN: 

(With the current PAM framework, that is doable)

[squell]

See commit 1efdab523bce2889d953a44d58a3b90089d24996 for a proof-of-concept.

[squell]

Re-opening since user info isn't shown yet.