[clang] [clang][analyzer] Add 'tmpfile' as an open function to SimpleStreamChecker (PR #70539)

[Ben Shi via cfe-commits]

benshi001 wrote:

> If I remember correctly there is somewhere in the clang documentation a file that refers to this checker, and the purpose of this checker is mostly documentation. I do not know if it is good to change the code or to extend this checker, because there is `StreamChecker` that should do the same checks but in more advanced way. Maybe @haoNoQ can tell more about this.

But the `StreamChecker` can not detect `DoubleCloseBugType`, while `SimpleStreamChecker` can.

https://github.com/llvm/llvm-project/pull/70539