feat: add Android ARMv8 (aarch64) build support

- Initialize Tauri Android project structure (gen/android)
- Fix desktop_dir() unavailability on Android in file_explorer.rs and serial.rs
- Fix minimize/maximize/unmaximize unavailability on Android in window.rs
- Remove updater:default permission from default capabilities (not available on Android)
- Update .gitignore for Android build artifacts
- Successfully builds APK for aarch64-linux-android target

src-tauri/capabilities/default.json

@@ -11,7 +11,6 @@
     "core:window:allow-set-size",
     "core:window:allow-start-dragging",
     "opener:default",
-    "process:default",
-    "updater:default"
+    "process:default"
   ]
 }