[K/N, K/JS, K/WASM] Enable FakeOverrideRebuilder by default

While not beeing final solution, this is closer to what
we want to have in the end. Enabling on non-JVM targets
would help better testing.

Enabling in JVM is now not possible yet, as some of the bugs are
not fixed yet (check KT-61360 for details)

^KT-62476

compiler/testData/ir/irText/classes/overriddenEquals.kt

@@ -0,0 +1,16 @@
+// FIR_IDENTICAL
+// KT-64271
+// IGNORE_BACKEND_K2: JVM_IR
+
+open class Base {
+    override fun equals(other: Any?): Boolean {
+        return this === other
+    }
+}
+
+interface I {
+
+}
+
+class Child1 : Base(), I
+class Child2 : I, Base()