[GH] Kmp-ify testutils-ktx

Upstreaming [Multiplatform Paging's kmp-ified testutils-ktx](https://github.com/cashapp/multiplatform-paging/tree/androidx-main-3.2.0-alpha04/testutils/testutils-ktx). See https://github.com/androidx/androidx/pull/505#issuecomment-1485536890 for more context.

Test: ./gradlew test connectedCheck
Bug: 270612487

This is an imported pull request from https://github.com/androidx/androidx/pull/518.

Resolves #518
Github-Pr-Head-Sha: a261291f3aefaeadefe1e397e4d489a80175db32
GitOrigin-RevId: 4d77f0bccbc3453555259ed09a23f266adf7061c

Change-Id: I2c3e46143ffa369aafed9bbc9da05d4b4636e6d0
diff --git a/testutils/testutils-ktx/build.gradle b/testutils/testutils-ktx/build.gradle
index 499d1ed..21ef343d 100644
--- a/testutils/testutils-ktx/build.gradle
+++ b/testutils/testutils-ktx/build.gradle
@@ -15,18 +15,35 @@
  */
 
 import androidx.build.LibraryType
-import org.jetbrains.kotlin.gradle.tasks.KotlinCompile
 
 plugins {
     id("AndroidXPlugin")
-    id("kotlin")
 }
 
-dependencies {
-    api(libs.kotlinStdlib)
-    api(libs.kotlinCoroutinesCore)
-    api(libs.kotlinCoroutinesTest)
-    api(libs.junit)
+androidXMultiplatform {
+    ios()
+    js {
+        nodejs()
+        binaries.executable()
+    }
+    jvm()
+    linux()
+    mac()
+
+    sourceSets {
+        commonMain {
+            dependencies {
+                api(libs.kotlinStdlib)
+                api(libs.kotlinCoroutinesCore)
+                api(libs.kotlinCoroutinesTest)
+            }
+        }
+        jvmMain {
+            dependencies {
+                api(libs.junit)
+            }
+        }
+    }
 }
 
 androidx {