Rework update of visibility and availability of UI elements

First update the visibility, then the availability (enabled or not), and
finally the value of the UI elements.

Changes:

• Disable Add User ID button if primary key is offline key
• Always show Certify button for OpenPGP keys (to allow cross-certification

of own keys); disable the button if no usable certification key is
available

• Disable Change Expiration button if primary key is offline key
• Disable Change Passphrase button for card keys
• Disable Generate Revocation Certificate button if primary key is offline

key

• GnuPG-bug-id: T5843