Uniformise error message when missing credentials and no tty

[davidferlay]

Current

• When an action requires a credential item which is missing from keyring, and that tty is not available (so no ability to prompt user for it), an error message is thrown:

$ time plasmactl bump --sync --keyring-passphrase XXX
 INFO  Processing propagation...
- Ansible vault password

• There is no visual error displayed, even though error code is thrown

• Message only says Ansible vault password

• These error message are currently implemented in each action making use of keyring

Expected

• If TTY is not available (ie action is running in CI), it would be great to raise a more user friendly error message likeERROR: "vaultpass" credential item is missing from keyring (and no tty)
• Would be great for these error message to be implemented in keyring itself, instead of having heterogeneous implementation across actions