Message for input device name nullity check

When building an input event, if ones forget to set the name of the
device, the only message debug info they got is this stacktrace

```
java.lang.NullPointerException
    at java.util.Objects.requireNonNull(Objects.java:208)
    at android.hardware.input.VirtualInputDeviceConfig.<init>(VirtualInputDeviceConfig.java:60)
```

Bug: N/A
Test: N/A
Flag: DOCS_ONLY
Change-Id: I7f1418b36176b3f6ff915e16929bd6416602fe3c