PGP improvements

[SergeyMosin]

1. Backed up OpenPGP keys can now be deleted from the server when they are deleted in the browser
2. Fixed: properly convert minutes to milliseconds for debounce function in Passphrases.handle
3. Added: An option to store(and delete) encrypted private key passphrase in the browser across multiple sessions
   • Passphrases are encrypted via window.crypto.subtle using salted accountHash as key material
   • Encrypted passphrases are stored in browser's localStorage
   • Stored passphrases can be removed in the Settings > Security

@the-djmaze I have added translations to en, de, nl, ru locale files. Is there a script to generate/copy translation keys to other localization files automatically or should just copy the "SOME_KEY":"english version" to all other locales ?