[Build] Move JUnit dependencies into the version catalog

The `kotlin-test` dependencies are left untouched as changing them affects publications, thus these versions are independent from the used inside our build
#KTI-1349 In Progress

libraries/tools/kotlin-assignment/build.gradle.kts

@@ -16,7 +16,7 @@ dependencies {
     commonCompileOnly(project(":compiler"))
     commonCompileOnly(project(":kotlin-assignment-compiler-plugin"))
 
-    testImplementation(commonDependency("junit"))
+    testImplementation(libs.junit4)
 }
 
 gradlePlugin {