Add test for authoritzation and limits

[Sjors]

The more tests the better of course, but this like the most security critical part:

cln-nostr-wallet-connect/src/main.rs

Lines 239 to 285 in 6450ad9

	// Check event is valid
	if event.verify().is_err() {
	info!("Event {} is invalid", event.id.to_hex());
	continue;
	}
	// info!("Got event: {:?}", serde_json::to_string_pretty(&event));
	// Check event is from correct pubkey
	if event.pubkey.ne(&connect_client_keys.public_key()) {
	// TODO: Should respond with unauth
	info!("Event from incorrect pubkey: {}", event.pubkey.to_string());
	continue;
	}
	// Decrypt bolt11 from content (NIP04)
	let content = match decrypt(
	&keys.secret_key()?,
	&connect_client_keys.public_key(),
	&event.content,
	) {
	Ok(content) => content,
	Err(err) => {
	info!("Could not decrypt: {err}");
	continue;
	}
	};
	// info!("Decrypted Content: {:?}", content);
	let request = match nip47::Request::from_json(&content) {
	Ok(req) => req,
	Err(err) => {
	warn!("Could not decode request {:?}", err);
	continue;
	}
	};
	// info!("request: {:?}", request);
	let event_builder = match request.params {
	nip47::RequestParams::PayInvoice(pay_invoice_param) => {
	handle_pay_invoice(
	&event,
	&keys,
	pay_invoice_param,
	cln_client.clone(),
	limits.clone(),

Maybe these lines can go in a helper function and then the tests can check that it returns true / false depending on some test vectors?