Add constructors to KtScope

- KtClassLikeSymbol.primaryConstructor was removed
- Constructors were removed from getCallableMembers because
constructors has no name (or special name `<init>`) and previous
implementation was incorrect
- KtScope.getAllSymbols returns constructors as before. Before it was
like this because of the incorrect implementation of getCallableMembers
- getConstructors has sence only for class scope,
for the rest cases it is empty

compiler/testData/asJava/lightClasses/OnlySecondaryConstructors.java

@@ -0,0 +1,6 @@
+public final class OnlySecondaryConstructors /* OnlySecondaryConstructors*/ {
+  public  OnlySecondaryConstructors();//  .ctor()
+
+  public  OnlySecondaryConstructors(int);//  .ctor(int)
+
+}