sd-bus: fix SASL reply to empty AUTH
    
    The correct way to reply to "AUTH <protocol>" without any payload is to
    send "DATA" rather than "OK". The "DATA" reply triggers the client to
    respond with the requested payload.
    
    In fact, adding the data as hex-encoded argument like
    "AUTH <protocol> <hex-data>" is an optimization that skips the "DATA"
    roundtrip. The standard way to perform an authentication is to send the
    "DATA" line.
    
    This commit fixes sd-bus to properly send the "DATA" line. Surprisingly
    no existing implementation depends on this, as they all pass the data
    directly as argument to "AUTH". This will not work if we want to pass
    an empty argument, though.
    
    Signed-off-by: David Rheinsberg <david.rheinsberg@gmail.com>
    (cherry picked from commit 2010873b4b49b223e0cc07d28205b09c693ef005)
    
    Related: #1838081
    
    patch_name: 0401-sd-bus-fix-SASL-reply-to-empty-AUTH.patch
    present_in_specfile: true
    location_in_specfile: 401
    squash_commits: true