[Gradle][Test] Add freeArgs to BuildOptions

libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/kotlin/org/jetbrains/kotlin/gradle/testbase/BuildOptions.kt

@@ -36,6 +36,7 @@ data class BuildOptions(
     val buildReport: List<BuildReportType> = emptyList(),
     val useFir: Boolean = false,
     val usePreciseJavaTracking: Boolean? = null,
+    val freeArgs: List<String> = emptyList(),
 ) {
     data class KaptOptions(
         val verbose: Boolean = false,
@@ -132,6 +133,9 @@ data class BuildOptions(
         if (usePreciseJavaTracking != null) {
             arguments.add("-Pkotlin.incremental.usePreciseJavaTracking=$usePreciseJavaTracking")
         }
+
+        arguments.addAll(freeArgs)
+
         return arguments.toList()
     }
 }