ShellMountPasswordDialog: Don't store password if volume can't be unlocked with it
As a follow up to !126 (merged), we should probably prevent storing the password if the user chose TCRYPT options which are not going to be stored but are required in addition to the password to unlock the volume.
Currently, when I open for example a hidden volume and check the "Remember Password" box, the next time I try to unlock the volume, GMountOperation first tries to unlock the volume in the background with the stored password. This takes about 15 seconds until it fails, because only the password is stored and not the fact that it's a hidden volume. After this, the unlock dialog opens, so that I can then successfully unlock the volume.
We could implement this by making the "Remember Password" checkbox unchecked and insensitive if any of the TCRYPT options were set by the user.