[Test] KT-61360: add tests for the IrFakeOverrideBuilder

Add tests for fake overrides with focus on java interoperability

Co-authored-by: Aleksandra Arsenteva <aleksandra.arsenteva@jetbrains.com>

compiler/testData/ir/irText/fakeOverrides/java21/sequenceSetIntersectionOverrideKJJ.kt

@@ -0,0 +1,32 @@
+// TARGET_BACKEND: JVM
+// JDK_KIND: FULL_JDK_21
+// WITH_STDLIB
+// SEPARATE_SIGNATURE_DUMP_FOR_K2
+// ^ ISSUE: KT-63914, KT-65219
+
+// FILE: 1.kt
+import java.util.*
+
+abstract class A : HashSet<Int>(), SequencedSet<Int> {
+    override fun spliterator(): Spliterator<Int> {
+        return null!!
+    }
+}
+
+class B : HashSet<Int>(), SequencedSet<Int>{
+    override fun reversed(): SequencedSet<Int> {
+        return null!!
+    }
+    override fun spliterator(): Spliterator<Int> {
+        return null!!
+    }
+}
+
+fun test(a: A, b: B){
+    a.size
+    a.addFirst(null)
+    a.reversed()
+
+    b.reversed()
+    b.addFirst(1)
+}