Extensibility: Pass the post object to allowed_block_types filter

[gziolo]

Description

Closes #2685.

This PR open an access to the current post to the allowed_block_types filter to make it possible to provide a different set of allowed block types per post type or based on other properties.

How has this been tested?

Manually added the following filter:

function my_test_allowed_block_types( $allowed_block_types, $post ) {
	if ( $post->post_type === 'post' ) {
		return $allowed_block_types;
	}
	return [ 'core/paragraph' ];
}
	
add_filter( 'allowed_block_types', 'my_test_allowed_block_types', 10, 2 );

Types of changes

Improvement.

Checklist:

• My code is tested.
• My code follows the WordPress code style.
• My code follows the accessibility standards.
• My code has proper inline documentation.

[gziolo]

@zgordon - can you give it a try?

[zgordon]

@gziolo do I just pill down latest Master to try this?

[gziolo]

Rather this branch: update/extensibility-allowed-block-types.

[noisysocks]

This @param comment is missing the name of the argument.

(It's weird that the linter didn't yell about this.)

[gziolo]

It's not a function, so it's tricky for both human and computer. I updated :)

[noisysocks]

👍 nice. This looks good to me once that @param is fixed up.

[zgordon]

Sweet! @gziolo can confirm it's working for me as expected :)