[FIR-TEST] Add new testdata generated after changes in previous commit

compiler/testData/diagnostics/tests/java8Overrides/overridingMethodOfAnyDiamond.fir.kt

@@ -0,0 +1,11 @@
+interface ILeft {
+    override fun toString(): String
+}
+
+interface IRight {
+    override fun toString(): String
+}
+
+interface IDiamond : ILeft, IRight {
+    override fun toString(): String = "IDiamond"
+}