Convert the app template to Kotlin (#36696)

Summary:
Pull Request resolved: facebook/react-native#36696

As the title says, we're converting the new app template to Kotlin.
This will reduce the template size and make it more aligned to market standards.

Changelog:
[Android] [Changed] - Convert the app template to Kotlin

Reviewed By: mdvacca

Differential Revision: D44142081

fbshipit-source-id: 6111360b6580460eba0341e47c55704cc673e444

Original-Commit: facebook/react-native@c1c22eb

Author: cortinico

template/template/android/app/build.gradle

@@ -1,4 +1,5 @@
 apply plugin: "com.android.application"
+apply plugin: "org.jetbrains.kotlin.android"
 apply plugin: "com.facebook.react"
 
 /**

template/template/android/build.gradle

@@ -9,6 +9,7 @@ buildscript {
 
         // We use NDK 23 which has both M1 support and is the side-by-side NDK version from AGP.
         ndkVersion = "23.1.7779620"
+        kotlinVersion = "1.7.22"
     }
     repositories {
         google()
@@ -17,5 +18,6 @@ buildscript {
     dependencies {
         classpath("com.android.tools.build:gradle")
         classpath("com.facebook.react:react-native-gradle-plugin")
+        classpath("org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlinVersion")
     }
 }