[MM-36058][MM-40572] Tray fixes (#1933)

* [MM-36058] Added config migration function, update default tray icon theme to system, allow Windows users to override icon theme

* [MM-40572] Restore minimize to tray option for Windows

* Lint fix

* Test fix

* Oops

src/common/config/defaultPreferences.ts

@@ -20,7 +20,7 @@ const defaultPreferences: ConfigV3 = {
     version: 3,
     teams: [],
     showTrayIcon: true,
-    trayIconTheme: 'light',
+    trayIconTheme: 'use_system',
     minimizeToTray: true,
     notifications: {
         flashWindow: 2,