[FIR] Set Java constructor source to Java class's when it's implicit

When there are no declared constructors in Java class, make
javaConstructor's source element point to the class declaration,
making it possible to navigate from constructor's invocation there.

^KTIJ-22360 Fixed

compiler/fir/java/src/org/jetbrains/kotlin/fir/java/FirJavaFacade.kt

@@ -640,7 +640,7 @@ abstract class FirJavaFacade(
     ): FirJavaConstructor {
         val constructorSymbol = FirConstructorSymbol(constructorId)
         return buildJavaConstructor {
-            source = javaConstructor?.toSourceElement()
+            source = javaConstructor?.toSourceElement() ?: javaClass.toSourceElement(KtFakeSourceElementKind.ImplicitConstructor)
             this.moduleData = moduleData
             isFromSource = javaClass.isFromSource
             symbol = constructorSymbol
@@ -687,9 +687,7 @@ abstract class FirJavaFacade(
         moduleData: FirModuleData,
     ): FirJavaConstructor {
         return buildJavaConstructor {
-            source = (javaClass as? JavaElementImpl<*>)
-                ?.psi
-                ?.toKtPsiSourceElement(KtFakeSourceElementKind.ImplicitConstructor) as? KtFakeSourceElement
+            source = javaClass.toSourceElement(KtFakeSourceElementKind.ImplicitConstructor)
             this.moduleData = moduleData
             isFromSource = javaClass.isFromSource
             symbol = FirConstructorSymbol(constructorId)