Enable SwiftLint rule 'toggle_bool' and fix all violations

.swiftlint.yml

@@ -162,7 +162,7 @@ whitelist_rules:
   - switch_case_on_newline
   - syntactic_sugar
   - todo
-#  - toggle_bool
+  - toggle_bool
 #  - trailing_closure
 #  - trailing_comma
   - trailing_newline

pass/Controllers/PasswordEditorTableViewController.swift

@@ -404,7 +404,7 @@ extension PasswordEditorTableViewController: FillPasswordTableViewCellDelegate {
 
     // show/hide password settings (e.g., the length slider)
     func showHidePasswordSettings() {
-        hidePasswordSettings = !hidePasswordSettings
+        hidePasswordSettings.toggle()
         tableView.reloadSections([passwordSection], with: .fade)
     }
 }