[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

generators/test-generator/build.gradle.kts

@@ -8,7 +8,7 @@ dependencies {
     testApi(project(":core:util.runtime"))
     testApi(projectTests(":compiler:test-infrastructure-utils"))
     testApi(kotlinStdlib())
-    testApi(commonDependency("junit:junit"))
+    testApi(libs.junit4)
     testApiJUnit5()
     testApi(project(":generators"))