Don't need footer with cancel button in read-only side modal forms

[david-crespo]

The X in the corner should be sufficient — there's no operation to "cancel". So it might be cool to add a flag to the form that lets us suppress the footer altogether. onSubmit is already optional, so maybe we just use that to hide the entire footer.

console/app/components/form/SideModalForm.tsx

Lines 130 to 146 in bdbc02b

	<SideModal.Footer error={!!submitError}>
	<Button variant="ghost" size="sm" onClick={onDismiss}>
	Cancel
	</Button>
	{onSubmit && (
	<Button
	type="submit"
	size="sm"
	disabled={!!submitDisabled}
	disabledReason={submitDisabled}
	loading={loading || isSubmitting}
	form={id}
	>
	{label}
	</Button>
	)}
	</SideModal.Footer>