Editor: Add localAutosaveInterval preference to editor settings

Backports changes from the Gutenberg plugin. Original PR in Gutenberg: WordPress/gutenberg#39180.

Props zieleadam, talldanwp.
See #55505.



git-svn-id: https://develop.svn.wordpress.org/trunk@53090 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-includes/block-editor.php

@@ -394,6 +394,8 @@ function get_block_editor_settings( array $custom_settings, $block_editor_contex
 		unset( $editor_settings['__experimentalFeatures']['spacing']['padding'] );
 	}
 
+	$editor_settings['localAutosaveInterval'] = 15;
+
 	/**
 	 * Filters the settings to pass to the block editor for all editor type.
 	 *