[FIR] Store matched actual class members inside FIR attribute

Currently, there is only attribute `ExpectForActualAttributeKey`
where mapping is stored only for source declarations with `actual`
modifier. But we need mapping of all class members, including classes
which were actualized via `actual typealias` or fake override members.
This data will be needed for the annotation checker in subsequent
commits.

^KT-60668
^KT-60936

compiler/testData/codegen/box/multiplatform/k2/actualInnerClassesFirMemberMapping.kt

@@ -0,0 +1,19 @@
+// LANGUAGE: +MultiPlatformProjects
+// IGNORE_BACKEND_K1: ANY
+// MODULE: common
+// FILE: common.kt
+expect class A {
+    class B {
+        fun foo()
+    }
+}
+
+// MODULE: main()()(common)
+// FILE: test.kt
+actual class A {
+    actual class B {
+        actual fun foo() {}
+    }
+}
+
+fun box() = "OK" // check no errors are thrown during building FIR member mapping