Remove WP5.8 notice if disable Gutenberg filters have already been added

Hello and thank you for this plugin!

Could you please check for the disabling Gutenberg filters, in the theme as well, before displaying the backend notice?

The Classic Widget plugin literally only has 2 lines of code:

// Disables the block editor from managing widgets in the Gutenberg plugin.
add_filter( 'gutenberg_use_widgets_block_editor', '__return_false' );
// Disables the block editor from managing widgets.
add_filter( 'use_widgets_block_editor', '__return_false' );

while this is handy for most inexperienced users / non devs, devs won’t use a plugin for just this and will add them directly to their custom theme, but your notice is there anyway.

Also, can you please add custom classes to your notice, so devs can hide it if necessary? 🙂

Thank you!!!