[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/generics/basicGenericMethodsOverride.kt

@@ -0,0 +1,41 @@
+// TARGET_BACKEND: JVM
+// FULL_JDK
+// WITH_STDLIB
+
+// FILE: Java1.java
+public class Java1 {
+    public <T> void foo(T a) { }
+    public <T> T bar() {
+        return null;
+    }
+}
+
+// FILE: 1.kt
+
+class A : Java1()
+
+class B : Java1() {
+    override fun <T : Any> foo(a: T?) { }
+    override fun <T : Any> bar(): T? {
+        return null!!
+    }
+}
+
+fun test(a: A, b: B) {
+    val k: Int = a.bar()
+    val k2: Int? = a.bar()
+    val k3: Any = a.bar()
+    val k4: Nothing = a.bar()
+    a.foo(1)
+    a.foo(null)
+    a.foo<Int?>(null)
+    a.foo(listOf(null))
+
+    val k5: Int? = b.bar<Int>()
+    val k7: Any? = b.bar<Any>()
+    val k8: Nothing? = b.bar<Nothing>()
+    b.foo(1)
+    b.foo(null)
+    b.foo<Int>(null)
+    b.foo(listOf(null))
+}