Refactor: Fix Event Buffer Deadlock with State Machine (#1633)

* feat: implement state machine for chat synchronization and buffer management

* test: Add Jest configuration and tests for connection deadlock handling

- Created a Jest configuration file to set up testing environment.
- Implemented utility functions for creating isolated authentication sessions and mocking WebSocket connections.
- Added a test case to ensure that the connection does not deadlock when history sync is disabled, verifying the correct handling of message events.

* feat: add GitHub Actions workflow for running tests

* chore: sort import lint

* fix: implement timeout handling for AwaitingInitialSync state in chat socket, maybe fix memory leak

* feat: enhance chat synchronization by refining AwaitingInitialSync handling and adding history sync checks

src/__tests__/binary/connection-deadlock.test.ts

@@ -0,0 +1,54 @@
+import { jest } from '@jest/globals'
+import { proto } from '../..'
+import { DEFAULT_CONNECTION_CONFIG } from '../../Defaults'
+import makeWASocket from '../../Socket'
+import { makeSession, mockWebSocket } from '../TestUtils/session'
+
+mockWebSocket()
+
+describe('Connection Deadlock Test', () => {
+	it('should not deadlock when history sync is disabled', async () => {
+		const { state, clear } = await makeSession()
+
+		state.creds.me = { id: '1234567890:1@s.whatsapp.net', name: 'Test User' }
+
+		const sock = makeWASocket({
+			...DEFAULT_CONNECTION_CONFIG,
+			auth: state,
+			shouldSyncHistoryMessage: () => false
+		})
+
+		const regularMessageListener = jest.fn()
+		sock.ev.on('messages.upsert', regularMessageListener)
+
+		// 1. Simulate receiving pending notifications. This activates the buffer.
+		sock.ev.emit('connection.update', { receivedPendingNotifications: true })
+
+		// 2. Now, emit a regular message. Because the previous step should have
+		// flushed the buffer, this message should be processed immediately.
+		const regularMessage = proto.WebMessageInfo.fromObject({
+			key: { remoteJid: '1234567890@s.whatsapp.net', fromMe: false, id: 'REGULAR_MSG_1' },
+			messageTimestamp: Date.now() / 1000,
+			message: { conversation: 'Hello, world!' }
+		})
+		sock.ev.emit('messages.upsert', { messages: [regularMessage], type: 'notify' })
+		// Wait for the event loop to process any final events.
+		await new Promise(resolve => setTimeout(resolve, 50))
+
+		// 3. Check if the regular message listener was called.
+		expect(regularMessageListener).toHaveBeenCalledTimes(1)
+		expect(regularMessageListener).toHaveBeenCalledWith(
+			expect.objectContaining({
+				messages: expect.arrayContaining([
+					expect.objectContaining({
+						key: regularMessage.key
+					})
+				]),
+				type: 'notify'
+			})
+		)
+
+		sock.end(new Error('Test completed'))
+		await clear()
+	})
+})