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/gen/android/buildSrc/build.gradle.kts

@@ -0,0 +1,23 @@
+plugins {
+    `kotlin-dsl`
+}
+
+gradlePlugin {
+    plugins {
+        create("pluginsForCoolKids") {
+            id = "rust"
+            implementationClass = "RustPlugin"
+        }
+    }
+}
+
+repositories {
+    google()
+    mavenCentral()
+}
+
+dependencies {
+    compileOnly(gradleApi())
+    implementation("com.android.tools.build:gradle:8.11.0")
+}
+