[LL FIR] rename testdata to testData to avoid copyright generation

We exclude testData pattern from copyright scope

analysis/low-level-api-fir/testData/inBlockModification/memberFunWithBodyWithContractScript.kts

@@ -0,0 +1,13 @@
+import kotlin.contracts.contract
+
+class A {
+    fun x() {
+        contract {
+            req
+        }
+
+        val a = <expr>doSmth("str")</expr>
+    }
+}
+
+fun doSmth(i: String) = 4