_add_plugin_file_editor_to_tools()
Function: Adds the ‘Plugin File Editor’ menu item after the ‘Themes File Editor’ in Tools for block themes.
Source: wp-admin/menu.php:284
_add_themes_utility_last()
Function: Adds the ‘Theme File Editor’ menu item to the bottom of the Appearance (non-block themes) or Tools (block themes) menu.
Source: wp-admin/menu.php:267