build: Add Kotlin to the project (#317)

- Added the 'org.jetbrains.kotlin.android' plugin to all module
build.gradle files and configured the Kotlin compiler JVM target to 1.8
in the root build.gradle.
- Updated the buildscript to use Kotlin version 2.2.0 and included the
Kotlin Gradle plugin classpath.

**Requirements**

- [ ] I have added test coverage for new or changed functionality
- [ ] I have followed the repository's [pull request submission
guidelines](../blob/main/CONTRIBUTING.md#submitting-pull-requests)
- [ ] I have validated my changes against all supported platform
versions

**Describe the solution you've provided**
I've added the Kotlin plugin and the configuration needed to be able to
add Kotlin code in future PRs

<!-- CURSOR_SUMMARY -->
---

> [!NOTE]
> Adds Kotlin support to all modules and configures the Kotlin Gradle
plugin with JVM target 1.8 in the root build.
> 
> - **Build/Gradle**:
> - Add Kotlin Gradle plugin (`kotlin_version = 2.2.0`) and classpath in
root `build.gradle`.
> - Configure `KotlinCompile` tasks with `jvmTarget = 1.8` for all
subprojects.
> - Apply `org.jetbrains.kotlin.android` plugin to `contract-tests`,
`example`, `launchdarkly-android-client-sdk`, and `shared-test-code`
modules.
> 
> <sup>Written by [Cursor
Bugbot](https://cursor.com/dashboard?tab=bugbot) for commit
1487407. This will update automatically
on new commits. Configure
[here](https://cursor.com/dashboard?tab=bugbot).</sup>
<!-- /CURSOR_SUMMARY -->

Author: agrognetti

build.gradle

@@ -1,9 +1,13 @@
-import java.time.Duration
 import com.android.build.gradle.BaseExtension
+import org.jetbrains.kotlin.gradle.dsl.JvmTarget
+import org.jetbrains.kotlin.gradle.tasks.KotlinCompile
 
 // Top-level build file where you can add configuration options common to all sub-projects/modules.
 
 buildscript {
+    ext {
+        kotlin_version = '2.2.0'
+    }
     repositories {
         mavenCentral()
         google()
@@ -14,6 +18,7 @@ buildscript {
         // For displaying method/field counts when building with Gradle:
         // https://github.com/KeepSafe/dexcount-gradle-plugin
         classpath("com.getkeepsafe.dexcount:dexcount-gradle-plugin:4.0.0")
+        classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
 
         // NOTE: Do not place your application dependencies here; they belong
         // in the individual module build.gradle files
@@ -71,6 +76,11 @@ subprojects { subproject ->
     plugins.withId("com.android.library") {
         configureAndroidModule(subproject)
     }
+    tasks.withType(KotlinCompile).configureEach {
+        compilerOptions {
+            jvmTarget = JvmTarget.JVM_1_8
+        }
+    }
     tasks.withType(JavaCompile).configureEach {
         // enable deprecation checks
         options.compilerArgs += "-Xlint:deprecation"

contract-tests/build.gradle

@@ -2,6 +2,7 @@ plugins {
     id("com.android.application")
     // make sure this line comes *after* you apply the Android plugin
     id("com.getkeepsafe.dexcount")
+    id 'org.jetbrains.kotlin.android'
 }
 
 android {

example/build.gradle

@@ -2,6 +2,7 @@ plugins {
     id("com.android.application")
     // make sure this line comes *after* you apply the Android plugin
     id("com.getkeepsafe.dexcount")
+    id 'org.jetbrains.kotlin.android'
 }
 
 android {

launchdarkly-android-client-sdk/build.gradle

@@ -3,6 +3,7 @@ plugins {
     id("signing")
     id("maven-publish")
     id("com.getkeepsafe.dexcount")
+    id 'org.jetbrains.kotlin.android'
 }
 
 group = "com.launchdarkly"

shared-test-code/build.gradle

@@ -1,7 +1,7 @@
-
 plugins {
     id("com.android.library")
     id("com.getkeepsafe.dexcount")
+    id 'org.jetbrains.kotlin.android'
 }
 
 group = "com.launchdarkly"