Add ActivityResultContract implementation for Login

Fixes line#150

dependencyVersion.gradle

@@ -13,6 +13,7 @@ ext {
 
             // API and runtime implementations
             androidx    : [
+                    activity        : "1.8.2",
                     annotation      : "1.1.0",
                     appcompat       : "1.1.0",
                     browser         : "1.2.0",

line-sdk/build.gradle

@@ -62,6 +62,7 @@ dependencies {
 
     implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:${ver.kotlin}"
 
+    implementation "androidx.activity:activity-ktx:${ver.androidx.activity}"
     implementation "androidx.annotation:annotation:${ver.androidx.annotation}"
     implementation "androidx.appcompat:appcompat:${ver.androidx.appcompat}"
     implementation "androidx.browser:browser:${ver.androidx.browser}"

line-sdk/src/main/java/com/linecorp/linesdk/auth/LineLogin.kt

@@ -0,0 +1,28 @@
+package com.linecorp.linesdk.auth
+
+import android.content.Context
+import android.content.Intent
+import androidx.activity.result.contract.ActivityResultContract
+
+class LineLogin : ActivityResultContract<LineLogin.Input, LineLoginResult>() {
+
+    data class Input(
+        val channelId: String,
+        val params: LineAuthenticationParams,
+        val isBrowserLoginOnly: Boolean = false
+    )
+
+    override fun createIntent(context: Context, input: Input): Intent {
+        val (channelId, params, isBrowserLoginOnly) = input
+        return if (isBrowserLoginOnly) {
+            LineLoginApi.getLoginIntentWithoutLineAppAuth(context, channelId, params)
+        } else {
+            LineLoginApi.getLoginIntent(context, channelId, params)
+        }
+    }
+
+    override fun parseResult(resultCode: Int, intent: Intent?): LineLoginResult {
+        return LineLoginApi.getLoginResultFromIntent(intent)
+    }
+
+}