Convert project to Kotlin

app/build.gradle

@@ -50,6 +50,7 @@ dependencies {
     implementation 'com.google.android.material:material:1.5.0-alpha01'
     implementation 'androidx.multidex:multidex:2.0.1'
     implementation 'androidx.preference:preference-ktx:1.1.1'
+    implementation 'androidx.test:core-ktx:1.4.0'
     testImplementation 'junit:junit:4.13.2'
     testImplementation 'org.robolectric:robolectric:4.1'
     googleImplementation 'com.google.firebase:firebase-core:19.0.0'