add more test

Author: Mohsen Azimi

test/remove-default-export-variable-assignment-transform/with-import/input.tsx

@@ -0,0 +1,3 @@
+import bar from 'bar';
+export default const foo: string = 'str';
+

test/remove-default-export-variable-assignment-transform/with-import/output.tsx

@@ -0,0 +1,3 @@
+import bar from 'bar';
+const foo: string = 'str';
+export default foo;