Feature request: Data property on forms for use in SSR lifecycles

[icopp]

Currently the form state is defined as just { errorMap, errors, values }, which makes it impossible to have a server action that also return non-value data. A simple example here would be a dropdown with options that can change after each form submit.

My suggestion would be something simple like a type annotation on formOptions, which if set would infer form state of { data, errorMap, errors, values }, with data then being included for purposes of form.Subscribe and so on. Server actions would return { ...state, data: { ... } } to change the data value, or { ...state, ...error.formState } in case of errors (reusing the existing data).