homectl: pick up cached/credential store/env var passwords *before* issuing first...

homectl: pick up cached/credential store/env var passwords *before* issuing first request

Previously, we'd generally attempt the operation first, without any
passwords, and only query for a password if that operation then fails
and asks for one. This is done to improve compatibility with
password-less authentication schemes, such as security tokens and
similar.

This patch modifies this slightly: if a password can be acquired cheaply
via the keyring password cache, the $CREDENTIALS_PATH credential store,
or the $PASSWORD/$PIN environment variables, acquire it *before* issuing
the first requested.

This should save us a pointless roundtrip, and should never hurt.