Add multiplatform test with substitution, fix deep supertypes

This commit fixes ambiguity problems introduced before
in MPP tests with deep supertypes

#KT-29636 Fixed

idea/testData/fir/multiModule/mppFakeOverrides/jvm/jvm.kt

@@ -0,0 +1,11 @@
+actual open class A<T> {
+    actual open fun foo(arg: T) {}
+    open fun bar(arg: T): T = arg
+}
+class D : C() {
+    // Fake: override fun bar(arg: CharSequence): String = super.bar(arg)
+    fun test() {
+        foo("")
+        bar("")
+    }
+}

idea/testData/fir/multiModule/mppFakeOverrides/jvm/jvm.txt

@@ -0,0 +1,21 @@
+FILE: jvm.kt
+    <T> public open actual class A {
+        public constructor(): super<R|kotlin/Any|>()
+
+        public open actual function foo(arg: R|T|): R|kotlin/Unit| {
+        }
+
+        public open function bar(arg: R|T|): R|T| {
+            return@@@bar <Unresolved name: arg>#
+        }
+
+    }
+    public final class D : R|C| {
+        public constructor(): super<R|C|>()
+
+        public final function test(): R|kotlin/Unit| {
+            R|FakeOverride</A.foo>|(String())
+            R|FakeOverride</A.bar>|(String())
+        }
+
+    }