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/Constructors.java

@@ -0,0 +1,12 @@
+public final class Constructors /* Constructors*/ {
+  private final int valInPrimary;
+
+  private  Constructors();//  .ctor()
+
+  public  Constructors(@org.jetbrains.annotations.NotNull() java.lang.String);//  .ctor(java.lang.String)
+
+  public  Constructors(int);//  .ctor(int)
+
+  public final int getValInPrimary();//  getValInPrimary()
+
+}