Convert the unit test from java to kotlin (#10702)

### Summary
This change converts the unit test from java to kotlin.

### Test plan
./gradlew :executorch_android:testDebugUnitTest

---------

Co-authored-by: Haiting Pu <[email protected]>

Author: phaiting

extension/android/executorch_android/build.gradle

@@ -9,6 +9,7 @@
 plugins {
     id "com.android.library" version "8.9.0"
     id "com.vanniktech.maven.publish" version "0.31.0"
+    alias(libs.plugins.jetbrains.kotlin.android)
 }
 
 android {
@@ -34,6 +35,9 @@ android {
             resources.srcDirs += [ 'src/androidTest/resources' ]
         }
     }
+    kotlinOptions {
+        jvmTarget = "1.8"
+    }
 }
 
 task copyTestRes(type: Exec) {
@@ -43,6 +47,7 @@ task copyTestRes(type: Exec) {
 dependencies {
     implementation 'com.facebook.fbjni:fbjni:0.5.1'
     implementation 'com.facebook.soloader:nativeloader:0.10.5'
+    implementation libs.core.ktx
     testImplementation 'junit:junit:4.12'
     androidTestImplementation 'androidx.test.ext:junit:1.1.5'
     androidTestImplementation 'androidx.test:rules:1.2.0'