fix: handle formdata correctly from form action

[crutchcorn]

When using a form like so:

export const handleForm = createServerFn('POST', async (formData: FormData, ctx) => {
});

<form action={handleForm.url} method="post" encType={"multipart/form-data"}/>

The form action would not be passed to the server handler appropriately. This PR fixes this behavior to work as-intended

[nx-cloud]

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nx run-many --target=test:e2e:replay

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