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

idea/idea-frontend-api/src/org/jetbrains/kotlin/idea/frontend/api/scopes/KtScope.kt

@@ -26,11 +26,13 @@ interface KtScope : ValidityTokenOwner {
         sequence {
             yieldAll(getCallableSymbols())
             yieldAll(getClassifierSymbols())
+            yieldAll(getConstructors())
         }
     }
 
     fun getCallableSymbols(nameFilter: KtScopeNameFilter = { true }): Sequence<KtCallableSymbol>
     fun getClassifierSymbols(nameFilter: KtScopeNameFilter = { true }): Sequence<KtClassifierSymbol>
+    fun getConstructors(): Sequence<KtConstructorSymbol>
 
     fun containsName(name: Name): Boolean = withValidityAssertion {
         name in getCallableNames() || name in getClassifierNames()

idea/idea-frontend-api/src/org/jetbrains/kotlin/idea/frontend/api/symbols/KtClassLikeSymbol.kt

@@ -54,8 +54,6 @@ abstract class KtClassOrObjectSymbol : KtClassLikeSymbol(),
 
     abstract val superTypes: List<KtTypeAndAnnotations>
 
-    abstract val primaryConstructor: KtConstructorSymbol?
-
     abstract override fun createPointer(): KtSymbolPointer<KtClassOrObjectSymbol>
 }