Gets i18n schema for block’s metadata read from `block.json` file.

function get_block_metadata_i18n_schema() {
	static $i18n_block_schema;

	if ( ! isset( $i18n_block_schema ) ) {
		$i18n_block_schema = wp_json_file_decode( __DIR__ . '/block-i18n.json' );
	}

	return $i18n_block_schema;
}