* Change passphrase generator's default wordSeparator to the empty string ''
* Create DefaultPassphraseGenerationOptions
* Use DefaultPassphraseGenerationOptions.wordSeparator in passphrase generation
* Add `empty` separator option to passphrase generator CLI and an example
* Change DefaultPassphraseGenerationOptions numWords to 3
* Use `DefaultPassphraseGenerationOptions.numWords` in CLI passphrase gen