separate declarations in libasm.h file and add list_push_front and list_size

srcs/bonus/ft_list_size.s

@@ -0,0 +1,19 @@
+global ft_list_size
+
+section .text
+
+ft_list_size:
+	xor rax, rax
+
+count_start:
+	test rdi, rdi
+	je end
+
+	mov rdi, [rdi + 8]
+
+	lea rax, [rax + 1]
+
+	jmp count_start
+
+end:
+	ret