Check platform<->impl compatibility for class members

When matching platform and impl classifiers, ensure that each declaration from
the platform class scope is present in the impl class scope.

Note that the presence of the 'impl' modifier is not checked yet

compiler/testData/multiplatform/classScopes/simple/common.kt

@@ -0,0 +1,5 @@
+platform class Foo(param: String) {
+    var property: Int
+
+    fun <T> function(p: List<T>): T
+}

compiler/testData/multiplatform/classScopes/simple/jvm.kt

@@ -0,0 +1,5 @@
+impl class Foo impl constructor(param: String) {
+    impl var property: Int = param.length
+
+    impl fun <T> function(p: List<T>): T = p.first()
+}

compiler/testData/multiplatform/classScopes/simple/output.txt

@@ -0,0 +1,8 @@
+-- Common --
+Exit code: OK
+Output:
+
+-- JVM --
+Exit code: OK
+Output:
+