Handle unsubscribes for extension's wasm node

[amaury1093]

substrate-light-ui/packages/extension-app/src/background/index.ts

Lines 68 to 78 in fccb563

	client.rpcSubscribe(JSON.stringify(jsonRpc), (res: string) => {
	try {
	port.postMessage({
	jsonRpc: { id: jsonRpc.id, ...JSON.parse(res) },
	origin: 'background',
	type: 'rpc.sendSubscribe',
	});
	} catch (error) {
	l.error(`rpcProxySubscribe: Error with ${res} - ${error.message}`);
	}
	});

We subscribe to the light node, but when the port closes, we don't actually call unsubscribe.

I guess we would need to store all the subscriptionIds, and on port.disconnect, call state_unsubscribeStorage() on all those ids.