State passphrase rules on passphrase creation screen

[leto]

Currently it's possible to input a very long passphrase twice, which may contain spaces for instance, and the user will get an error that spaces are not valid at the very end.

Telling users exactly which characters are valid in passphrases avoids these kind of UI/UX issues.

Additionally, why are spaces not valid? Is it technical or to prevent users from confusing seed phrases and passphrases?

[leto]

@SamouraiDev ping