Customize template options

Hey team. Currently, the only way I can specify a template is with a string:

```

```

I may be missing something, but how would we go about customizing the template options? For example, say we want to disable the `powered_by` option? It does't look like there's a way

Start at the ConvertKitForm component and the template prop shown in the issue, then trace how template options are passed to the rendered form. Determine how an option such as powered_by could be disabled while preserving the existing template string usage. Done means callers can customize that option through the component API, with the behavior verified in the relevant tests if they exist.

Written by the indexing model from the issue text.