Raw FIR: introduce FirConstructor.isPrimary

compiler/fir/tree/src/org/jetbrains/kotlin/fir/declarations/FirConstructor.kt

@@ -13,6 +13,8 @@ import org.jetbrains.kotlin.fir.visitors.FirVisitor
 @BaseTransformedType
 interface FirConstructor : @VisitedSupertype FirFunction, FirCallableMemberDeclaration {
 
+    val isPrimary: Boolean get() = false
+
     override val isOverride: Boolean get() = status.isOverride
 
     val delegatedConstructor: FirDelegatedConstructorCall?

compiler/fir/tree/src/org/jetbrains/kotlin/fir/declarations/impl/FirPrimaryConstructorImpl.kt

@@ -21,4 +21,7 @@ class FirPrimaryConstructorImpl(
     isActual: Boolean,
     delegatedSelfTypeRef: FirTypeRef,
     delegatedConstructor: FirDelegatedConstructorCall?
-) : FirConstructorImpl(session, psi, symbol, visibility, isExpect, isActual, delegatedSelfTypeRef, delegatedConstructor)
+) : FirConstructorImpl(session, psi, symbol, visibility, isExpect, isActual, delegatedSelfTypeRef, delegatedConstructor) {
+    override val isPrimary: Boolean
+        get() = true
+}