Throw error when using meth_caller with non-public methods

Throw error when using meth_caller with non-public methods

Summary:
Currently, Hack does not throw an error if you use `meth_caller` on a public or private method from within the same class hierarchy.

```
class Foo extends MyChild {
  protected function bar(): void {}
  private function baz(): void {}

  public function test(): void {
    $y = meth_caller(Foo::class, 'bar');
    $z = meth_caller(Foo::class, 'baz');
  }
}
```

Currently, using this reference will result in a HHVM runtime error, as we don't support this yet. We will in the future, so make this controllable via an option in both `hh_single_type_check` and `.hhconfig` so that we don't need another release to change this in the future.

`hh_single_type_check --meth_caller_only_public_visibility=false $t`

and the

`meth_caller_only_public_visibility = false`

option in `.hhconfig` will stop Hack from throwing these errors.

Reviewed By: periodic1236

Differential Revision: D28136384

fbshipit-source-id: 4aa9d8cc085c51a22ad92776d3a787c7e715d941