[Ast differ] Add type parameter instantiation test
[Ast differ] Add type parameter instantiation test

Summary: The test added here is to show the difference of the subsequent commit.

Reviewed By: nmote, dsainati1

Differential Revision: D10282326

fbshipit-source-id: 94d169e4f5011d70020afba99c96c87d1bccf746

nmote/flow,nmote/flow,nmote/flow,nmote/flow,nmote/flow,nmote/flow,nmote/flow