Discriminate header classes in favor of non-header type aliases

In the test case, the problem was that Foo.a's type was resolved to the
_class A_, which was written to metadata on JVM instead of the class
AImpl with typealias A as an abbreviation. This metadata was incorrect
because there's no class A from the JVM compiler's point of view; that's
why the error "cannot access class A" was reported

 #KT-19151 Fixed

compiler/testData/multiplatform/implTypeAlias/discriminateHeaderClassInFavorOfTypeAlias/common.kt

@@ -0,0 +1,3 @@
+class Foo(val a: A? = null)
+
+header class A

compiler/testData/multiplatform/implTypeAlias/discriminateHeaderClassInFavorOfTypeAlias/jvm.kt

@@ -0,0 +1,5 @@
+impl typealias A = AImpl
+
+class AImpl {
+    fun jvm(): A = this
+}

compiler/testData/multiplatform/implTypeAlias/discriminateHeaderClassInFavorOfTypeAlias/jvm2.kt

@@ -0,0 +1 @@
+val a = Foo().a?.jvm()

compiler/testData/multiplatform/implTypeAlias/discriminateHeaderClassInFavorOfTypeAlias/output.txt

@@ -0,0 +1,11 @@
+-- Common --
+Exit code: OK
+Output:
+
+-- JVM --
+Exit code: OK
+Output:
+
+-- JVM (2) --
+Exit code: OK
+Output: