Static template that doesn't parse the response

With a current use case, the response from the POST isn't important - the side effect is handled by `path-deps` and that handles the re-render. It is only important to let the user know there if was an error.

As such, it would be helpful to be able to provide a static template block that does not parse the response.

For example:
```html

Some static message explaining that an unknown error was encountered.

Submit

```

Using the [available template engines](https://v1.htmx.org/extensions/client-side-templates/) causes a Parsing error in Javascript when JSON isn't returned by a 500 error and htmx falls back to inserting the response into "#unhandled-error" instead of the static message.

Being able to force the static message to display would be very beneficial.