lang: replace stack-based parser with a recursive parser

lang/ast/ident.c

@@ -1,4 +1,3 @@
-#include "ctx.h"
 #include "node.h"
 
 #include <fx/ds/string.h>
@@ -14,6 +13,5 @@ static void to_string(struct ivy_ast_node *node, fx_string *str)
 
 struct ast_node_type ident_node_ops = {
 	.n_to_string = to_string,
-	.n_state_size = sizeof(struct parser_state),
 	.n_node_size = sizeof(struct ivy_ast_ident_node),
 };