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.kt

@@ -0,0 +1,9 @@
+// OnlySecondaryConstructors
+
+class OnlySecondaryConstructors {
+    constructor(): super()
+    constructor(p: Int): this()
+}
+
+// LAZINESS:NoLaziness
+// FIR_COMPARISON