Add @(init) attribute for procedures, allowing for procedures to be called at startup

These procedures will be called after global variables have been initialized as normal

src/parser.hpp

@@ -174,6 +174,7 @@ struct AstPackage {
 	Array<AstFile *>      files;
 	Array<AstForeignFile> foreign_files;
 	bool                  is_single_file;
+	isize                 order;
 
 	MPMCQueue<AstPackageExportedEntity> exported_entity_queue;