[K/N] Samples: Migrate 'echoServer' to modern multiplatform

^KT-50547 Fixed

kotlin-native/backend.native/tests/samples/build.gradle.kts

@@ -49,7 +49,7 @@ val buildSamplesWithPlatformLibs by tasks.creating {
     dependsOn(":workers:assemble")
 
     if (isMacos || isLinux) {
-        dependsOn(":echoServer:assemble") // https://youtrack.jetbrains.com/issue/KT-50547
+        dependsOn(":echoServer:assemble") //https://youtrack.jetbrains.com/issue/KT-63721/
         dependsOn(":nonBlockingEchoServer:assemble")
         dependsOn(":tensorflow:assemble")
     }

kotlin-native/backend.native/tests/samples/echoServer/build.gradle.kts

@@ -1,33 +1,22 @@
-import org.jetbrains.kotlin.gradle.plugin.mpp.KotlinNativeTargetPreset
+import org.jetbrains.kotlin.gradle.plugin.mpp.KotlinNativeTarget
 
 plugins {
     kotlin("multiplatform")
 }
 
-val additionalPresets: List<KotlinNativeTargetPreset> = listOf("linuxArm64").map {
-    kotlin.presets[it] as KotlinNativeTargetPreset
-}
-
 kotlin {
-    // Determine host preset.
-    val hostOs = System.getProperty("os.name")
+    macosX64()
+    macosArm64()
+    linuxArm64()
+    linuxX64()
+    /*
+    https://youtrack.jetbrains.com/issue/KT-63721/Commonizer-Uncovered-platform.posix.socket-not-commonized-for-mingw-linux-macos
+    Not building for windows, because it would require writing expect/actuals around
+    signed vs unsigned socket APIs:
+    mingwX64()
+     */
 
-    // Create a target for the host platform.
-    val hostTarget = when {
-        hostOs == "Mac OS X" -> macosX64("echoServer")
-        hostOs == "Linux" -> linuxX64("echoServer")
-        hostOs.startsWith("Windows") -> mingwX64("echoServer")
-        else -> throw GradleException("Host OS '$hostOs' is not supported in Kotlin/Native $project.")
-    }
-
-    // Create cross-targets.
-    val additionalTargets = additionalPresets.map { preset ->
-        val targetName = "echoServer${preset.name.capitalize()}"
-        targetFromPreset(preset, targetName) {}
-    }
-
-    // Configure executables for all targets.
-    configure(additionalTargets + listOf(hostTarget)) {
+    targets.withType<KotlinNativeTarget>().configureEach {
         binaries {
             executable {
                 entryPoint = "sample.echoserver.main"
@@ -35,17 +24,4 @@ kotlin {
             }
         }
     }
-
-    sourceSets {
-        val echoServerMain by getting
-        additionalPresets.forEach { preset ->
-            val mainSourceSetName = "echoServer${preset.name.capitalize()}Main"
-            getByName(mainSourceSetName).dependsOn(echoServerMain)
-        }
-    }
-
-    // Enable experimental stdlib API used by the sample.
-    sourceSets.all {
-        languageSettings.optIn("kotlin.ExperimentalStdlibApi")
-    }
 }

kotlin-native/backend.native/tests/samples/echoServer/gradle.properties

@@ -1,2 +1 @@
 kotlin.code.style=official
-kotlin.import.noCommonSourceSets=true