Add playground example for async coroutine builder

Author: LukasLechnerDev

app/src/main/java/com/lukaslechner/coroutineusecasesonandroid/playground/coroutinebuilders/2_async.kt

@@ -0,0 +1,34 @@
+package com.lukaslechner.coroutineusecasesonandroid.playground.coroutinebuilders
+
+import kotlinx.coroutines.async
+import kotlinx.coroutines.delay
+import kotlinx.coroutines.runBlocking
+
+fun main() = runBlocking<Unit> {
+
+    val startTime = System.currentTimeMillis()
+
+    val deferred1 = async {
+        val result1 = networkCall(1).also {
+            println("result received: $it after ${elapsedMillis(startTime)}ms")
+        }
+        result1
+    }
+
+    val deferred2 = async {
+        val result2 = networkCall(2)
+        println("result received: $result2 after ${elapsedMillis(startTime)}ms")
+        result2
+    }
+
+    val resultList = listOf(deferred1.await(), deferred2.await())
+
+    println("Result list: $resultList after ${elapsedMillis(startTime)}ms")
+}
+
+suspend fun networkCall(number: Int): String {
+    delay(500)
+    return "Result $number"
+}
+
+fun elapsedMillis(startTime: Long) = System.currentTimeMillis() - startTime