[FIR2IR] Always look for already generated fake overrides before creating them

This change covers the case where some f/o was generated in common module
  and it is referenced in platform code. But signature of this f/o may be
  different in different modules because of e.g. actualization of value
  parameters with actual typealias

^KT-60850 Fixed

compiler/testData/codegen/box/fakeOverride/substitutionInLocal.kt

@@ -0,0 +1,22 @@
+// MODULE: lib
+// FILE: l.kt
+
+open class LightParam : LightVariab<Unit>() { // i/o public String getName
+}
+
+open class LightVariab<W> {
+    fun W.name(): String? = "O"
+    val W.name2: String? get() = "K"
+}
+
+// MODULE: main(lib)
+// FILE: m.kt
+
+fun box(): String {
+    return object : LightParam() {
+        fun getText() = Unit.name() + Unit.name2
+    }.getText()
+}
+
+
+