DEV: Rename fill_input -> set_input in AceEditor page object (#31825)

Follow up to dd015af0b8

spec/system/admin_editing_objects_typed_theme_setting_spec.rb

@@ -122,7 +122,7 @@ RSpec.describe "Admin editing objects type theme setting", type: :system do
 
       theme_settings_editor = admin_customize_themes_page.click_theme_settings_editor_button
 
-      theme_settings_editor.fill_in(<<~SETTING)
+      theme_settings_editor.set_input(<<~SETTING)
       [
         {
           "setting": "objects_setting",

spec/system/page_objects/components/ace_editor.rb

@@ -8,7 +8,7 @@ module PageObjects
         self
       end
 
-      def fill_input(content)
+      def set_input(content)
         # Can't rely on capybara here because ace editor is not a normal input.
         page.evaluate_script(
           "ace.edit(document.getElementsByClassName('ace')[0]).setValue(#{content.to_json})",
@@ -17,7 +17,7 @@ module PageObjects
       end
 
       def clear_input
-        fill_input("")
+        set_input("")
       end
 
       def editor_input

spec/system/page_objects/components/admin_theme_settings_editor.rb

@@ -8,8 +8,8 @@ module PageObjects
         self
       end
 
-      def fill_in(settings)
-        editor.fill_input(settings)
+      def set_input(settings)
+        editor.set_input(settings)
         self
       end