[Feature Request] Make use statements of nonexistant entities raise a typechecker error

### HHVM Version

```
HipHop VM 4.11.0 (rel)
Compiler: 1561398047_114259580
Repo schema: 520e2fedfb82e52f9393995caea047ec425b15ce
hackc-fc15a7f638ec69c8fdb7df14b24dc3cc49fda256-4.11.0
```

### Operating System and Version
```Ubuntu 18.04```

### Standalone code, or other way to reproduce the problem
```HACK
use function Foo\Bar\Baz\Qux\nonexistant;
```

### Actual result
```
No errors!
```

### ~Expected~ Desired result
```
Typing[4090] Could not find function Foo\Bar\Baz\Qux\nonexistant in
--> example.hack
1 | use function Foo\Bar\Baz\Qux\nonexistant;
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^
````