ClientAuthV3 fixes

* Remove Client Auth as an explicit option (it's on by default).
 * Update wording about Public mode
 * Fix tuple error when raising TorTooOldStealth exception in CLI
 * Move Private Key button next to URL button in GUI
 * Replace visual references of ClientAuth to Private Key
 * Remove HTTPAuth Flask dependency and remove a lot of code to do with password generation,
   401 auth triggers/invalid password rate limit detection etc
 * Test updates
 * Remove obsolete locale keys

cli/onionshare_cli/mode_settings.py

@@ -37,8 +37,6 @@ class ModeSettings:
         self.default_settings = {
             "onion": {
                 "private_key": None,
-                "hidservauth_string": None,
-                "password": None,
                 "client_auth_priv_key": None,
                 "client_auth_pub_key": None,
             },
@@ -48,7 +46,6 @@ class ModeSettings:
                 "public": False,
                 "autostart_timer": False,
                 "autostop_timer": False,
-                "client_auth": False,
                 "service_id": None,
             },
             "share": {"autostop_sharing": True, "filenames": []},