Add support for placeholder attribute to component

app/components/form_elements/fieldset_resettable_setting_component.rb

@@ -2,7 +2,7 @@
 
 module FormElements
   class FieldsetResettableSettingComponent < ViewComponent::Base
-    def initialize(tag: "li", key:, type: :text, title:, description: nil)
+    def initialize(tag: "li", key:, type: :text, title:, description: nil, placeholder: nil)
       @tag         = tag
       @positioning = :vertical
       @title       = title
@@ -10,6 +10,7 @@ module FormElements
       @key         = key.to_sym
       @type        = type
       @resettable  = is_resettable?(@key)
+      @placeholder = placeholder
     end
 
     def is_resettable?(key)