Fixes #194.

Given this post_content:

<!-- wp:code {"highlightedLines":"2"} -->
<pre class="wp-block-code"><code>if ( a &lt; b ) {
   alert( 'A is less than B!' );
}</code></pre>
<!-- /wp:code -->

This renders as a Code block that looks like this:

If then this new PHP filter is added:

add_filter( 'syntax_highlighting_code_block_styling', '__return_false' );

Any styling is omitted from being added to the frontend:

It's then up to the developer to add the required styling.

This will also prevent adding the Customizer controls for styling, while also moving them to the bottom when they are enabled.

Before	After	Styles Turned Off