[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/sequenceSetIntersectionOverrideKJK.kt

@@ -0,0 +1,55 @@
+// TARGET_BACKEND: JVM
+// JDK_KIND: FULL_JDK_21
+// WITH_STDLIB
+
+// FILE: 1.kt
+import java.util.*
+abstract class A : SortedSet<Int>, Set<Int>
+
+abstract class B(override val size: Int) :  SortedSet<Int>, Set<Int> {
+    override fun reversed(): SortedSet<Int> {
+        return null!!
+    }
+
+    override fun first(): Int {
+        return 1
+    }
+}
+
+abstract class C : SortedSet<Int?>, MutableSet<Int?>
+
+abstract class D : SortedSet<Int?>, MutableSet<Int?> {
+    override fun reversed(): SortedSet<Int?>? {
+        return null!!
+    }
+
+    override fun addLast(e: Int?) { }
+}
+
+fun test(a: A, b: B, c: C, d: D){
+    a.size
+    a.add(1)
+    a.remove(1)
+    a.addFirst(1)
+    a.addLast(null)
+    a.removeFirst()
+    a.removeLast()
+    a.reversed()
+    a.first
+
+    b.reversed()
+    b.first
+
+    c.size
+    c.add(1)
+    c.remove(1)
+    c.addFirst(1)
+    c.addLast(null)
+    c.removeFirst()
+    c.removeLast()
+    c.reversed()
+    c.first
+
+    d.reversed()
+    d.addLast(null)
+}