This PR defines the block attributes centrally in PHP. This allows for plugins to easily change the default values for a block's attributes. For example, if a site wants all blocks to have wrapped lines and have PHP selected by default, they can do so with this code:

add_action( 'init', function() {
	$block_type = WP_Block_Type_Registry::get_instance()->get_registered( 'core/code' );
	$block_type->attributes['language']['default'] = 'php';
	$block_type->attributes['wrapLines']['default'] = true;
} );

The great thing about this is that the defaults will be reflected in the editor and for every instance of the generic Code block already created when rendered on the frontend.

This PR also removes obsolete deprecated block definition which is now only relevant in mkaz/code-syntax-block.