feat: move websocket client to sdk, always restart ws client

[mochiruntime]

Closes #268

Note: the WS client was copy pasted from query-client, however the restart mechanism bit was added:

graasp-sdk/src/frontend/ws-client.ts

Lines 95 to 133 in 2a433d6

	// native client WebSocket instance
	let ws: WebSocket;
	const assignWsClient = () => {
	console.debug('restarting ws client');
	ws = new WebSocket(wsHost);
	let keepAlive: ReturnType<typeof setInterval>;
	// on close, recreate connection
	ws.addEventListener('close', () => {
	clearInterval(keepAlive);
	assignWsClient();
	});
	// keep alive on error, trigger close event
	ws.addEventListener('error', (error) => {
	console.error(error);
	ws.close();
	});
	// ad-hoc ping mechanism
	ws.addEventListener('open', () => {
	let ttl = 2;
	keepAlive = setInterval(() => {
	if (ttl <= 0) {
	ws.close();
	return;
	}
	// note: we abuse that sending a "ping" string will result in a bad request response
	ws.send('ping');
	ttl = ttl - 1;
	}, 30000);
	ws.addEventListener('message', () => {
	ttl = 2;
	});
	});
	return ws;
	};
	ws = assignWsClient();

[spaenleh]

This Looks good to me ! Thank you @dialexo 💪