Add Kotlin support

As Android team we've agreed to only use Kotlin for new code. Let's get
the ball rolling for Notes too.

Signed-off-by: Álvaro Brey <alvaro.brey@nextcloud.com>

Author: AlvaroBrey

app/build.gradle

@@ -1,4 +1,5 @@
 apply plugin: 'com.android.application'
+apply plugin: 'org.jetbrains.kotlin.android'
 
 android {
     compileSdkVersion 33
@@ -89,6 +90,7 @@ dependencies {
 
     // Android X
     implementation 'androidx.appcompat:appcompat:1.6.0'
+    implementation 'androidx.core:core-ktx:1.9.0'
     implementation 'androidx.core:core-splashscreen:1.0.0'
     implementation 'androidx.fragment:fragment:1.5.5'
     implementation 'androidx.lifecycle:lifecycle-viewmodel-ktx:2.5.1'

build.gradle

@@ -1,12 +1,16 @@
 // Top-level build file where you can add configuration options common to all sub-projects/modules.
 
 buildscript {
+    ext {
+        kotlinVersion = '1.8.0'
+    }
     repositories {
         mavenCentral()
         google()
     }
     dependencies {
         classpath 'com.android.tools.build:gradle:7.4.0'
+        classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlinVersion"
 
         // NOTE: Do not place your application dependencies here; they belong
         // in the individual module build.gradle files
@@ -19,10 +23,16 @@ allprojects {
         google()
         maven { url "https://jitpack.io" }
     }
+
 }
 
 subprojects {
     tasks.withType(Test) {
         maxParallelForks = Runtime.runtime.availableProcessors().intdiv(2) ?: 1
     }
-}
+    tasks.withType(org.jetbrains.kotlin.gradle.tasks.KotlinCompile) {
+        kotlinOptions {
+            jvmTarget = "11"
+        }
+    }
+}