Make stdlib work with -Xmultifile-package-facades.

Fixed wrong owner mapping in presence of -Xmultifile-package-facades.
Fixed backing field mapping issue.
Added more tests.

compiler/testData/codegen/boxInline/multifileClasses/inlineFromOtherPackage.2.kt

@@ -1,4 +1,6 @@
 @file:[JvmName("MultifileClass") JvmMultifileClass]
 package a
 
-inline fun foo(body: () -> String): String = body()
+inline fun foo(body: () -> String): String = bar(body())
+
+public fun bar(x: String): String = x