[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/basicWilcardsOverride.fir.kt.txt

@@ -0,0 +1,65 @@
+class A : Java1 {
+  constructor() /* primary */ {
+    super/*Java1*/()
+    /* <init>() */
+
+  }
+
+}
+
+class B : Java1 {
+  constructor() /* primary */ {
+    super/*Java1*/()
+    /* <init>() */
+
+  }
+
+  override fun bar(): MutableList<out Number> {
+    return CHECK_NOT_NULL<Nothing>(arg0 = null)
+  }
+
+  override fun bar2(): MutableList<in Number> {
+    return CHECK_NOT_NULL<Nothing>(arg0 = null)
+  }
+
+  override fun bar3(): MutableList<*> {
+    return CHECK_NOT_NULL<Nothing>(arg0 = null)
+  }
+
+  override fun foo(a: MutableList<out Number>?) {
+  }
+
+  override fun foo2(a: MutableList<in Number>?) {
+  }
+
+  override fun foo3(a: MutableList<*>?) {
+  }
+
+}
+
+fun test(a: A, b: B) {
+  a.foo(a = null)
+  a.foo(a = mutableListOf<@FlexibleNullability Number?>(elements = [null]))
+  a.foo(a = listOf<Int>(element = 1))
+  a.bar() /*~> Unit */
+  a.foo2(a = null)
+  a.foo2(a = mutableListOf<Number?>(elements = [null]))
+  a.foo2(a = mutableListOf<@FlexibleNullability Number?>(elements = [1.1]))
+  a.bar2() /*~> Unit */
+  a.foo3(a = null)
+  a.foo3(a = mutableListOf<Nothing?>(elements = [null]))
+  a.foo3(a = listOf<Nothing?>(element = null))
+  a.foo3(a = listOf<String>(element = ""))
+  a.bar3() /*~> Unit */
+  b.foo(a = null)
+  b.foo(a = mutableListOf<Int>(elements = [1]))
+  b.bar() /*~> Unit */
+  b.foo2(a = null)
+  b.foo2(a = mutableListOf<Number?>(elements = [null]))
+  b.foo2(a = mutableListOf<Number>(elements = [1.1]))
+  b.bar2() /*~> Unit */
+  b.foo3(a = null)
+  b.foo3(a = mutableListOf<Nothing?>(elements = [null]))
+  b.foo3(a = mutableListOf<String>(elements = [""]))
+  b.bar3() /*~> Unit */
+}