Disable password generation suggestion for password fields (#238)

Firefox comes with generally great security features like "Firefox
Lockwise" [1], but the suggestion to generate a new random password when
focusing a password field [2] is kind of annoying and not necessary due
to the usage of a password manager that includes a password generator.
Therefore it has now been disabled.

[1]: https://www.mozilla.org/firefox/lockwise
[2]: https://wiki.mozilla.org/Toolkit:Password_Manager/Password_Generation

Closes GH-227

snowblocks/firefox/user.js

@@ -504,6 +504,15 @@ user_pref("security.OCSP.enabled", 1);
 user_pref("security.webauth.webauthn_enable_softtoken", false);
 user_pref("security.webauth.webauthn_enable_usbtoken", false);
 
+/*
+ * Disable the password generation suggestion for password fields.
+ * References:
+ *   - https://wiki.mozilla.org/Toolkit:Password_Manager/Password_Generation
+ *   - https://www.mozilla.org/firefox/lockwise
+ *   - https://blog.mozilla.org/firefox/password-security-features
+ */
+user_pref("signon.generation.enabled", false);
+
 /*
  * Always ask to save logins and passwords for websites.
  * Available within the UI under: