test: 添加 Demo25 示例项目

playground/Demo/Demo25/Main.snow

@@ -0,0 +1,23 @@
+module: Main
+    import: os,ModuleA
+    globals:
+        declare c: int = 10
+    function: main
+        returns: void
+        body:
+             c = ModuleA.getA()
+             os.print(c)
+        end body
+    end function
+end module
+
+module: ModuleA
+    globals:
+        declare a: int = 2
+    function: getA
+        returns: int
+        body:
+            return a
+        end body
+    end function
+end module

playground/Demo/Demo25/OS.snow

@@ -0,0 +1,11 @@
+module: os
+    import: os
+    function: print
+        params:
+            declare i1: int
+        returns: void
+        body:
+            syscall("PRINT",i1)
+        end body
+    end function
+end module