Implemented Clean architecture, removed redundant dependencies

core/build.gradle

@@ -11,4 +11,7 @@ java {
 dependencies {
     implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk8:$kotlin_version"
     implementation "org.jetbrains.kotlinx:kotlinx-coroutines-android:$coroutines_version"
-}
+
+    testImplementation "junit:junit:$junit_version"
+    testImplementation "org.jetbrains.kotlinx:kotlinx-coroutines-test:$coroutines_test_version"
+}