ATS plugins are too tolerant of loading bad configs

With ATS plugins like header rewrite the loaders themselves are very tolerant of errors inside the config files themselves, typically only blocking ATS starts and reloads when config files are missing. This is done by returning TS_ERROR from TSRemapNewInstance.

Example of header rewrite that should block reload:

```
# mistype of condition:
cond %{PSEUDO__REMAP_HOOK}
```

This might require further investigation of what might be required.