v7.2.1: Simplified output directory handling

Simplified the selection of destination directory, so it only occurs at PDF Save time.

Also, corrected the (not Trezor compatible) SLIP-39 passphrase handling.

Improved Paper Wallet handling, and separate Paper format (eg. Letter, Legal, A4, Photo), and Card Layout (eg. index, credit, photo, etc.) DO NOT USE for production: all Paper Wallets are encrypted with the fixed password "password".