fix(electron): add icon for AppImage build (#6257)

1. the icon is fixed in `/Applications`: https://github.com/toeverything/electron-forge-maker-appimage/commit/128b8c22f9b2e088ce4f88057749b0a8cd55ca98#diff-a694a3e854f53b066e34ec310e05bd18b4944c016455f6963f54a351784d5fa6L91
2. the App's icon MUST be 64x64 png and set via `setIcon`

![image](https://github.com/toeverything/AFFiNE/assets/584378/bbce0007-066b-413f-a85a-193acbbe5c13)

packages/frontend/electron/src/main/main-window.ts

@@ -5,6 +5,7 @@ import { BrowserWindow, type CookiesSetDetails, nativeTheme } from 'electron';
 import electronWindowState from 'electron-window-state';
 
 import { isLinux, isMacOS, isWindows } from '../shared/utils';
+import { buildType } from './config';
 import { mainWindowOrigin } from './constants';
 import { ensureHelperProcess } from './helper-process';
 import { logger } from './logger';
@@ -76,6 +77,12 @@ async function createWindow(additionalArguments: string[]) {
     },
   });
 
+  if (isLinux()) {
+    browserWindow.setIcon(
+      join(__dirname, `../resources/icons/icon_${buildType}_64x64.png`)
+    );
+  }
+
   nativeTheme.themeSource = 'light';
 
   mainWindowState.manage(browserWindow);