[FIR] Forbid multiple labels per statement

^KT-53629: Fixed

compiler/testData/diagnostics/tests/controlStructures/nestedLoopsWithMultipleLabels.fir.kt

@@ -0,0 +1,10 @@
+// K2: See KT-65342
+
+fun test() {
+    <!MULTIPLE_LABELS_ARE_FORBIDDEN!>a@<!> b@ while(true) {
+        val f = {
+            return@a
+        }
+        break@b
+    }
+}